In Disguise by the other witch

Severus hated admitting it even to himself, but he had that soft spot in him when it came to the clumsy idiot's parents. He knew Minerva took Longbottom to the St. Mungos. In fact, it was part of Severus' plan. His mind ran back a few days to the private meeting in Albus' office.

“Minerva,” Albus turned to the witch, the only person present apart from Severus and the Headmaster. “I had asked Severus to come up with a plan to keep Harry safe- “

“- or as safe as possible,” Severus muttered loud enough for both the Headmaster and his deputy to hear.

“- and Severus came back with a rather unique idea-“ Albus continued smoothly only to be interrupted again with Severus' rude mutter.

“- nothing unique about it.” Severus knew he was insolent but sometimes he couldn't help himself. His old teachers made him feel like an unruly student.

Minerva shot him a disapproving glance, Albus once again ignored him.

“Severus will impersonate Neville and to keep a close eye on Harry on the Saturday outing.”

“Why not keeping Harry at Hogwarts?” Minerva countered. “Even Severus admits that Harry won't be safe enough in Hogsmeade.”

“We all know that went so well in his third year,” Severus reminded her.

“Well, I can keep an eye on him this time. God knows his behavior leaves something to be desired this year. I can give him a detention without any regret.” Minerva offered.

“Nice to hear you say that Potter is a rude obnoxious brat.” Severus smirked.

“Severus, please,” Dumbledore interjected before Minerva could respond. “Minerva, I think Harry's behavior – yes, I also have noticed it has grown worse since last school year – would only continue to worsen if we confine him to the castle.”

“What about Neville, though,” Minerva objected. “He can be confined? And without reason, I might add?”

“Severus thinks Neville would willingly trade Hogsmeade for St. Mungos.”

Minerva's face softened. “I sometimes need to remind myself that there beats a warm heart behind the cold exterior of yours, Severus.”

There was a cold heart behind his cold exterior, whatever Minerva thought. He had a heart as cold as ice with a few traitorous warm weak spots. One of the spots was the Longbottoms. Severus even didn't really know why.

He remembered Frank from school. He had been a good enough guy. Once he – a Gryffindor prefect – had saved Severus' hide. Back then, Severus had been just a miserable third year, picked on even by his own house. That unexpected act of mercy was remembered and appreciated, but it wasn't the reason for his weakness.

Maybe Severus felt guilty for being a part of the group that debilitated Alice and Frank, even if he hadn't been present at their attack. Or maybe he felt sorry for them – trapped in a non-living, not-dying state. Severus knew for sure that he would prefer death, merciful in her definiteness. They, though, were left hanging. And their pathetic whimpy boy had been raised by Frank's mother. Also, according to Minerva, Augusta Longbottom had taken ill. It was feared that her vulture on hat and her might not see the end of the school year.