As soon as they returned to 12 Grimmauld Place Sirius chewed violently through the rope tying him and transformed back into his human form; Snape sent for Dumbledore via the floo network.

‘You’ll pay for that,’ Sirius spat furiously, with traces of the growl he had as a dog prevalent in his tone.

‘For what Black?’ Snape said, his lips curling into a sneer. ‘Preventing your capture and imprisonment by the park-keeper or for returning you to where you are supposed to be?’

‘Don’t tell me where I’m supposed to be!’ Sirius snarled, removing the rope from his neck. He threw himself down in a chair at the kitchen table with the air of a petulant child. After a few moments silence Snape followed suite, wheeling a watchful Harry to a position next to him.

‘Doggy?’ Harry ventured, but he was greeted with a wall of silence.

Sirius and Snape glared at each other over the table, their eyes locked in a ferocious battle of wills. Sirius’s wild black pupils, that stretched indistinguishably over his dark irises as a result of many years in Azkaban, met unflinchingly the reflective, marble eyes of Snape which never gave anything away. After several moments it was Harry that broke the silence.

‘Snape!’ he said, tugging at the man’s trouser leg from his position in his pushchair. ‘Up.’

Snape turned to look sharply at Harry; Sirius leant back in his chair, his arms folded lazily and his head cocked to one side.

‘Looks like the kid wants some attention,’ Sirius said. ‘It’s funny though, I didn’t realise that you had a child that no-one knew anything about. I’m sure it will make a most interesting story for Dumbledore when he gets here, don’t you think?’

Snape didn’t reply. He watched Harry who was pulling at his trousers. It was obvious that he was desperate to be changed but Snape had no intention of doing so in front of Sirius. The problem was that Harry wasn’t likely to keep up his so-far patient demeanour. Very soon it would be tears, screaming and fists.

‘Up,’ Harry insisted again. He didn’t understand why Snape was refusing to listen to him and he was beginning to get crotchety. It seemed forever since he’d been wet, and to top it off he’d been taken to a weird kitchen in a weird house with a weird man who he was sure had been a dog only minutes before. It was very confusing.

‘So whose is he?’ Sirius pressed. ‘Or is he spawned of the devil? I here your master’s got allsorts working for him these days.’

Snape turned away from Harry to sneer at Sirius. ‘It seems strange to me, Black, that Dumbledore himself hasn’t filled you in on exactly who this is. But, then again, perhaps after disobeying his instructions to accompany Potter to platform nine-and-three-quarters he has decided to teach you a lesson. A lesson, I might add, that it doesn’t appear you have learned.’ Snape pressed his fingertips slowly together before continuing, ‘I wonder how many death eaters have seen you about London this time?’

Sirius, to his annoyance, felt his face flame. He knew as well as Snape did that he had been banned (though not in so many words) from leaving Grimmauld Place. Being caught by Snape today in Hyde Park was akin to being found with his hand in a large cookie jar; it angered him to think that Snape, his sworn enemy, was most probably going to witness the reproach that was sure to come from Dumbledore when he finally arrived.

He had been half-hoping that Snape had been somewhere where he wasn’t supposed to be. He might have known that he was acting on Dumbledore’s orders and that Dumbledore knew all about the toddler he had with him. No-one seemed to tell Sirius anything anymore. They were treating him like a troublesome child. He was sick of Molly telling him to ‘think with his head’ and ‘control his temper’ – both of which were difficult when he was living within the slowly shrinking (or so it seemed like) walls of the ancient house of the Blacks, with his mother’s ever-screaming presence on the stairs.

‘Who is it then?’ he snapped.

Snape’s lips curled even wider, ‘If Dumbledore wanted you to know then he would have told you,’ he said shortly.

Sirius got to his feet and sent his chair clattering to the floor. ‘Don’t mess with me Snivellus,’ he said angrily, baring his teeth automatically; they were unusually sharp and crooked and Harry began to whimper.

Snape merely changed his expression to look as though he was slightly bored. If Sirius had looked carefully, however, he would have seen his opponents hand clench around his wand buried deep in the blue flannel cardigan. ‘Sit down Black,’ he said.

‘Don’t tell me what to do!’ Sirius barked.

At that, however, Harry disturbed the pair once again. He had been very frightened with the big bang that the chair had made as it had fallen to the floor and he didn’t like the dogman’s wild black eyes, or the way he was shouting at Snape. He covered his face and began to cry, kicking his legs against the pushchair and punctuating his sobs with ear-piercing screams.

Snape closed his eyes momentarily as though in pain. Sirius got up and walked over to the pushchair, kneeling a foot in front of it, which increased the volume of the screams tenfold.

‘Quiet little thing, isn’t he?’ Sirius said flinching at the latest round of wailing.

‘Quiet Potter,’ Snape snapped automatically, ‘it was a chair not an earthquake.’

‘So full of patience … ’ Sirius began sarcastically. Suddenly he snapped his head round to face Snape. ‘Hang on, what did you call him?’

Snape hesitated only for a moment. ‘Potter,’ he said.

‘This kid is one of James’ relatives?’ Sirius asked confused, watching Harry carefully now.

‘I told you to ask Dumbledore,’ Snape said abruptly, annoyed that he had given himself away, and more annoyed by Harry’s wailing. He got to his feet and unbuckled the straps of the pushchair, taking Harry brusquely into his arms.

‘Stop that racket,’ Snape said, ‘anyone would think that you had been decapitated by a werewolf.’

Harry took no notice. His arms flailed around and his sobs deepened. He had been on the verge of tears since he the first moment he’d felt that his nappy was wet and he was enjoying letting it all out.

‘I’m asking you,’ Sirius said, stepping in front of Snape and Harry.

‘COLDY’ Harry squawked loudly, his small fist connecting with Snape’s cheek and catching him off guard.

‘That’s quite enough of that, Potter,’ Snape said, restraining Harry’s arms with his free hand and looking directly into his deep green eyes, ‘unless you want the back of your hand slapped again?’

Harry pouted at that, as Sirius grinned. ‘I’m beginning to like you,’ he said pleasantly to Harry. ‘Looks like you might have given Snape here a shiner – well done.’

Harry beamed at the dogman. Snape’s harsh tone had silenced him temporarily. He knew that he shouldn’t have hit out, but he was getting very frustrated. The kitchen was warm but he was cold and besides which the bobble hat felt like it was choking him.

‘Off, off,’ Harry said, and before Snape could stop him he wrenched the hat off his head, revealing to a dumbfounded Sirius a shock of jet black hair and a pronounced scar shaped like a lightening bolt.

‘Harry?’ Sirius said weakly.

Harry regarded Sirius for a few seconds before recognition dawned as well. ‘See-rus!’ he shouted happily, holding his arms open. He knew that he knew the dogman from somewhere – in a flash a memory came back to him and this time it didn’t go anywhere. See-rus had once let him sit on a huge shiny red bike that had flown round and round the garden. When the pretty lady with the green eyes – his mother, Lily - had come home she had shouted and hit See-rus with a big rolled up paper. Harry had laughed and laughed.

It was in that moment of recognition that Dumbledore appeared to a whirl of activity in the grate.

‘Good afternoon gentleman,’ Dumbledore said brightly.

‘See-rus,’ Harry insisted, forgetting his nappy and holding his arms out for cuddle from the funny man. Snape, however, was holding him fast. Harry struggled slightly, twisting himself in Snape’s arms, but Snape merely repositioned him.

‘What is going on here?’ Sirius asked furiously, whirling to face Dumbledore. ‘Why is Harry a baby and why hasn’t anyone thought to tell me about it?’

‘Perhaps, Black, because we suspected that, as usual, you would let your feelings on the matter overshadow your judgment,’ Snape suggested with a raised eyebrow.

‘I’M NOT TALKING TO YOU!’ Sirius roared.

Immediately Harry’s bottom lip began to tremble.

‘Sirius, please, shall we talk about this calmly,’ Dumbledore said, ‘you appear to be scaring Harry.’ He held his arms out for the frightened baby and this time Snape willingly gave him up.

‘Balbus,’ Harry whimpered. ‘That’s right Harry,’ Dumbledore said, holding Harry up and jiggling him around a bit. ‘Have you had a good time in the park with Professor Snape?’

Harry nodded. ‘Birdies,’ he said. Snape snorted and Harry seemed to understand. ‘Swans,’ he corrected himself. Snape looked mildly impressed.

‘Good-boy, Harry,’ Dumbledore said. ‘Now perhaps Snape could get that dirty nappy off you whilst I have a little world with Sirius?’

Snape was horrified. ‘Headmaster I must insist that you hear what I have to say,’ he said.

‘All in good time, Severus,’ Dumbledore said. ‘I think we owe Sirius an explanation as to Harry’s condition first. And I must say Severus, I had hardly realised that your expedition to the park would have taken you so far of track as to end up in Grimmauld Place.

Sirius looked of unease equalled Snape’s indignant expression.

‘I ensure you, headmaster,’ Snape said haughtily, ‘that I had no intention of ending up here. I found Black wandering unsupervised, posing as a stray in Hyde Park. He was in the process of being captured by the park-keeper when I intervened.'

Sirius flushed a deep red which covered his gaunt, pale face as he looked guiltily at Dumbledore. The word ‘unsupervised’, however, rankled with him. He had suspected for a while that Dumbledore had asked the Order to keep an eye on him. They were always popping into headquarters unannounced.

Sirius expected anger from Dumbledore but all he saw was a sad disappointment that was much worse. He felt like he was teenager again and had just been sent before the headmaster for putting Peter Pettigrew in danger with one of his thoughtless pranks.

‘I see,’ Dumbledore said. He didn’t even seem to notice Harry tugging at his beard. ‘Can you please take Harry next door and change him Severus?’

Snape didn’t protest this time, though he could scarcely hide his displeasure – he had hoped to witness Sirius being rebuked by Dumbledore. He prised Harry’s fingers from Dumbledore’s beard and transported him and the baby-bag next door.

Sirius couldn’t even raise a smirk at the thought of Snape changing Harry’s nappy. He knew that he had let Dumbledore down, and that was bad enough, but worse than that, something awful had happened to Harry and no-one had trusted him enough to tell him. He sat down wearily.

‘What happened?’ he said.

‘Harry was victim to a powerful black curse wielded by Draco Malfoy.’

‘Malfoy?’ Sirius said with surprise, ‘Lucius’s son?’

‘Yes. We do not believe, however, that the curse was Draco’s but simply something that he had picked up from his father and used in anger – unfortunately a curse which has been tailored for someone quite indistinguishable from Harry, at least in some ways, otherwise it would not have had such an effect. It caused him to de-age to fifteen months almost a week ago.’

‘The age he was when Lily and James …’

‘Yes. It might be significant or it might not. Severus has been doing everything he can to solve the riddle.’

Sirius snorted, ‘Well he doesn’t appear to be trying very hard does he?’

‘Sirius,’ Dumbledore said calmly. ‘Severus has spent every free minute with Harry; he has caused him to age three months in a week.’

‘Wow, at this rate it will only be a year till he’s back to normal,’ Sirius muttered sarcastically. ‘That’s if Voldemort doesn’t get to him first of course.’

‘We have taken all the measures possible to ensure Harry’s protection.’

‘That’s funny,’ Sirius said. ‘I was sure I saw him and Snape wandering around Hyde Park today without so much as an escort.’

A slightly ominous silence followed this remark and Sirius had the decency to look ashamed.

‘Let’s have a cup of tea shall we?’ Dumbledore said at last.

A few minutes later and a smiling Harry and a disgusted-looking Snape returned to the kitchen.

‘Tea?’ Dumbledore said brightly. Snape took the offered cup without a word and summoned a high chair to sit Harry in, giving him one of the jam sandwiches that Molly had provided for the trip. Sirius looked dubious at the apparent thought that went into this but he didn’t say anything – he certainly wasn’t going to compliment Snape on his parenting skills.

‘So you’re Harry are you?’ Sirius said, smiling as Harry smeared jam over his face. ‘You were always were mischievous. Lily said you got it from James – you father – he was a little sod too at your age apparently.

‘Sod, sod, sod’ Harry chanted, pleased to have learnt a new word.

Dumbledore’s eyes twinkled. ‘Please be careful what you say, Sirius, Molly was most insistent that we not teach Harry – ah – any strong words.’

‘Sorry,’ Sirius said grinning. ‘I meant you were a little tyke,’ he corrected. Harry held his jam sandwich out to Sirius, he felt like he’d made a new (old) friend.

‘If we can get to the matter in hand, headmaster,’ Snape said, pursing his lips at the way Sirius fussed over Harry.

‘And what’s that then, Snape?’ Sirius said dangerously, giving his attention back to the sneering man.

‘I would like to know why exactly you were parading around in Hyde Park when, as I have told the headmaster on several occasions, Peter Pettigrew has already informed Voldemort and his death eaters exactly what form you take as an animagus and Lucius Malfoy has been able to identify you in London at Kings Cross station. I mean really Black, I know that you feel useless stuck in here with nothing significant to do. But playing round a known apparition point? That’s a bit too much even for you.’

‘I wasn’t playing,’ Sirius said through gritted teeth.

‘Scaring children and chasing birds wasn’t it? It doesn’t sound much like work to me – in fact it sounds rather selfish, especially when there are people putting themselves in danger to protect you.’

Sirius rounded on Snape, his wand in his hand in an instant. ‘You better watch your mouth, Snape,’ he spat. ‘I know who you are. You don’t fool me. I know that you’re only keeping Harry like this on your “master’s” orders.’

‘Gentleman,’ Dumbledore said, holding up his hand, ‘this is getting us nowhere. Please sit down.’ His tone was even but there was a command behind it that would endure no argument. Slowly Snape and Sirius, rather like two school-boys caught fighting, separated and sat down, watching each other carefully.

Harry giggled. ‘Fight, fight!’ he said clapping his hands. He liked seeing Snape getting told off by Balbus it made a change from him being told off by Snape.

‘Eat your sandwich, don’t paint your face with it,’ Snape snapped. Harry’s bottom lip pushed out in a sulk – evidently the change wasn’t going to last very long.

‘Why wasn’t I told?’ Sirius said at last, looking down at the table.

‘We didn’t think it wise,’ Dumbledore said gently. ‘I know how much you care about Harry, Sirius, and I know that you would take great personal risk to protect him. I did not want you to …’

‘Do anything rash?’ Sirius finished angrily.

‘Well you certainly have the track record, Black,’ Snape interrupted. ‘You still do not seem to have enlightened us as to today’s little expedition.’

At that Sirius got to his feet and grabbed a muggle newspaper off the kitchen cabinet. He threw it on the table in front of Snape.

‘Been scrabbling around in the bin again, Black?’ Snape said, ‘Or were you just being a good dog?’

‘Severus,’ Dumbledore said with just a hint of warning.

Snape opened the newspaper and read the headline. ‘Muggle disappearances,’ he read unimpressed. ‘I fail to see how this has any relevance.’

‘That is an early edition of the Evening Standard,’ Sirius said. ‘At ten o’ clock this morning three young boys disappeared when they were skiving school, quite near to where you were with Harry actually - so perhaps you better reconsider exactly how safe it is to take him to the park.’

‘Fascinating,’ Snape said.

‘They just disappeared,’ Sirius said ignoring him, ‘that’s the third report of muggle disappearances around this area in the past two weeks. More than that, the other children with them reported seeing a skull-shaped cloud in the sky. Of course no-one believes them.’

‘The Dark Mark,’ Dumbledore said, stroking his beard absentmindedly.

‘That was my thoughts. I apparated to the park to see if I could find anything more out about it. It’s a known apparition point in that area and I thought I could try and well …’

Sirius trailed off. When he was relaying the story back to Dumbledore he realised how stupid it sounded. If death eaters had taken some muggle children they would hardly hang around to be caught.

Sirius had just wanted to feel like he was actually doing something. He was sick of hanging around ‘taking care of headquarters’, watching Lupin and Mad-Eye return exhausted from a hard day’s work, when the most useful thing he could do was to make them a cup of tea. He hadn’t escaped from Azkaban only to be confined to the house by the Order, and endure the snide remarks of Snape.

Dumbledore sighed. ‘Make sure that Nymphadora, Remus and Alastor are informed,’ he said, ‘ask them to make some enquiries with our muggle contacts.’

‘Yes, of course,’ Sirius said bitterly, ‘tell the people who are actual members of the Order rather than simply being humoured.’

Snape looked triumphant.

‘You are a member of the Order, Sirius,’ Dumbledore said patiently. ‘You are simply incapacitated at the present time.’ He paused. ‘But please I must insist that you do not leave the house for the time being. You are too important for us to lose.’

Snape smiled mirthlessly. ‘Oh very important,’ he said, 'after all someone has to clean headquarters and make sure the rest of us have tea to drink.’

‘At least I don’t spend my time licking the boots of your “Dark Lord”’ Sirius shot back, his hand clenching once again around his wand. ‘Tell me Snape, did he punished you well for not making a quicker appearance after the Triwizard tournament?’

Snape looked ready to explode. Just as he was about to get to his feet and curse Sirius, however, Dumbledore intervened.

‘That’s quite enough, Sirius,’ Dumbledore said, his blue eyes showing the first gleam of fire.

Sirius, perhaps realising he had gone too far, suddenly changed tack. ‘If Harry is going to be a baby for a while, surely there’s no safer place for him that here at Grimmauld Place? I could watch him.’

This request calmed Snape almost immediately as he sensed a chance to gain freedom. ‘That suits me,’ he said, fighting to regain his composure (and eyeing the mess that Harry was making of his sandwich disdainfully). ‘Someone with as much time on his hands as Black is far more suited to babysitting than I.’

‘I’m afraid Harry must stay in Severus’s care, for now at least,’ Dumbledore said kindly.

‘I see,’ Sirius said curtly.

‘It’s not that you wouldn’t do an excellent job,’ Dumbledore went on. ‘But for the present time Severus needs every spare moment to work on the problem in hand. Out of the members of the Order, Severus is the most familiar with black magic.’

‘Well as he was - or is - a death eater for Voldemort that’s hardly surprising,’ Sirius said. He was angry. Having Harry there would have been a welcome distraction.

Snape grabbed his wrist. ‘Don’t say the Dark Lord’s name,’ he said through gritted teeth.

‘Burns does it?’ Sirius mocked. ‘Well how can you be so sure that Voldemort won’t figure out what you’re doing? You’re still going to the meetings aren’t you?’

Snape jumped as though he had been scalded at the second mention of his former master’s name. His wrist burned like it had been splashed with molten ash. Death eaters were banned from both speaking and hearing the Dark Lord’s name and were punished with a searing pain when they did.

‘Hurty?’ Harry enquired, dropping the crust of his sandwich onto the little table of his high chair. There seemed to be a lot of arguments going on and he didn’t know whether he liked it all that much.

‘I’m fine, Potter,’ Snape snapped, massaging his wrist. ‘Black here just likes his little games. It makes him feel important.’

‘You didn’t answer my question,’ Sirius said.

‘Severus is of course attending meetings. He is one of our most valuable contacts. Harry, however, is quite safe. You have my word,’ Dumbledore said.

‘Oh I forgot how proficient you were at Occlumency,’ Sirius said scornfully. ‘Makes it rather difficult to tell whose side you are really on though, don’t you think?’

‘Sirius,’ Dumbledore said quietly, ‘we are all on the same side, perhaps we could act like it.’

Sirius had a lot more to say on the matter, but out of respect for Dumbledore he held his tongue.

‘Now,’ said Dumbledore, ‘perhaps you would like to spend some time with your godson before he returns to Hogwarts? Severus has a potions lesson that he is most eager not to miss and I’m sure he could do with the break.’

Dumbledore seemed determined to make the two men act like a team in some form.

Sirius smiled for the first time since he had met. ‘Of course,’ he said. ‘You don’t mind keeping me company for a few hours do you Harry?’

‘Bike?’ Harry said, his eyes widening as he looked at the dogman.

‘You remember that do you?’ Sirius said grinning. ‘No the bike’s gone I’m afraid, but I’m sure we can find you something up in the attic. Mum put all mine and Regulus’s old toys in there.’

Harry nodded and held his arms out to Sirius who lifted him up high above his head.

‘Look, you’re flying Harry,’ Sirius said, ‘Zoom, zoom.’ He moved Harry up and down the room making flying noises; Harry squealed and giggled till he was breathless.

‘I’ll send someone for him after school,’ Snape said curtly, his thin eyebrow raised in derision. He crossed to the grate.

‘Bye Snape,’ Harry said, waving his hand furiously.

With such a watchful audience Snape felt like he couldn’t ignore the excited toddler, ‘Bye Potter,’ he muttered abruptly before disappearing in the grate.

Later that evening when Harry was tucked up in bed, exhausted from the fun afternoon he had spent with See-rus, Tonks made her report to Dumbledore. It seemed that the children who were the latest ‘disappeared’ muggles were all part of the same family - the Pickles family of Bethnal Green. The muggle police were treating them as runaways, common to the high-rise estate in which they lived. They had disregarded the halloween mask found close to the place the boys were last seen – a mask that Snape would later identify as the one distributed to the Dark Lord’s death-eaters upon initiation.