Snape and Harry are locked into the Room of Requirement by Dumbledore.  Harry has his magic, but Snape does not.  The Room makes Harry witness a miserable childhood memory with the Dursleys.  To Harry’s horror, he is forced to witness the memory again, this time with Snape.  Once back in the Room, Snape goads Harry, who orders the Room to give Snape exactly what he deserves.  The two of them witness four possible fates for Snape.  The Room produces two bottles of Veritaserum.  Snape questions a dosed Harry, but then, when it his turn, replaces the truth serum with water and fakes Harry out.  The Room produces the Mirror of Erised, and through that, Harry discovers that Snape loved Lily.  Harry demands that Snape teach him to Occlude,  because Voldemort cannot know Snape’s true loyalties.  Harry learns to Occlude by using the power of his grief.  After a disastrous attempt to blast their way out of the Room, Harry heals his burned hands  

 The Room sends our duo to Snape’s childhood, where they meet the child Severus and the child Lily.  Harry attempts to warn his small mother of her future, and is forced to Obliviate both children.  The Sorting Hat appears, and Harry uses it to get the Sword of Gryffindor, which gouges a tunnel out of the Room.  Snape cannot use the tunnel, however, and Harry refuses to leave him.  Snape tells him that he was the one to tell Voldemort of the prophesy, correctly guessing that this knowledge will get Harry to leave.  Harry goes and finds a room with a pensieve.  He cannot unlock the door to Dumbledore’s office until he views the memory, so he does.  It is Harry’s memory--removed by Dumbledore--of the night his parents died.  Infuriated, Harry goes back to Snape rather than to Dumbledore.  Snape is in bad shape, so Harry heals him.  The two of them reach a new understanding, and, together, go back through the tunnel and face Dumbledore.

Snape and Harry make Dumbledore take an Unbreakable Vow to tell the truth and question him about everything that happened in the Room.  Harry updates Ron and Hermione. They agree to use the Fidelius Charm so that Voldemort cannot torture them about what Harry told them.  To do the charm, they must all view a dark secret of Harry’s, that he contemplated killing himself when he was a child. This infuriates Snape, who slaps Harry.  Angst ensues.  Dumbledore summons Harry, who reluctantly goes to see him.  Dumbledore tells him that he must kill Voldemort, and reveals that because of Ariana’s death, he decided not to take Harry in.  An upset Harry rips up Dumbledore’s photo of Ariana and leaves.  Umbridge gives Harry and his friends detention.  Afterward, Snape heals Harry and shows him his quarters, as a neutral place they can talk.  They fight, however, and Snape gives Harry detention.  Harry sulks, so Snape distracts him by pulling out a box of carefully guarded photographs, and shows Harry a picture of Lily’s parents.  Harry worries about Dumbledore’s apparent disappearance and tells Snape he believes Dumbledore is in the Room.  Snape goes to check, and when he returns,  he nearly beats Harry with a belt when he thinks Harry has destroyed his precious box of photographs.  This incident leaves both of them deeply shaken.

Harry again voices his worries about Dumbledore, and the two return to the Room.  This time, with Harry’s help, they are able to enter, and find Dumbledore.  Bottles of Veritaserum pop into existence and harrass Snape until he agrees to drink it--for real this time.  After he drinks it, Dumbledore puts Harry in a body-bind so he cannot interfere and prepares to question Snape...