When Harry explores them, he learns everything he needs to know. In his dying moments, Snape asks Harry to look at him - clearly a reference to Lily, in that Harry's eyes resemble his mother's - and gives him a vial of memories. Unbeknownst to both Voldemort and Snape, Harry, Ron, and Hermione have been hiding and watching the entire scene unfold, and when Voldemort leaves the room, Harry rushes forward to try to save Snape. Horrified, Harry tries to chase Snape, but he disappears with his fellow Death Eaters. And that's when Snape shows up and does the job himself. However, when the young bully corners a weakened Dumbledore, it seems like the wisened wizard is able to convince his terrified student to spare his life. including Draco, who's been tasked by Voldemort with killing the headmaster. In the midst of all of this, Harry and Dumbledore work together constantly to understand Voldemort's life and uncover his secrets, but their mission comes to a screeching halt when they return to Hogwarts after a night away to find the school overtaken by Death Eaters. In other words, he was the potions genius who's been helping Harry excel at the art of potion-making all year. Plus, Snape is the so-called Half-Blood Prince. Despite Ron's and Hermione's doubts, Harry is correct that Voldemort himself has enlisted Draco with a task, though he doesn't know that task is until it's too late. Well, both roads ultimately lead to Snape.

Of course, when Sirius eventually escapes, Snape is livid, creating even more tension between him and Harry. Even though Harry, Ron, and Hermione attack him so that he doesn't turn Sirius in, he shows up at the last minute and tries to protect our heroes when Lupin turns into a werewolf (hence the monthly potion) and attacks everybody there. However, Snape isn't a stick in the mud all the time. As a result, he refuses to help bring down Pettigrew and tries to arrest his old enemy. Though Snape is handed the truth about Sirius on a silver platter, his hatred of the wizard clouds his judgment, as Sirius was once his schoolyard rival. Though Harry believes that Sirius - James and Lily's best friend - sold them out to Voldemort, the truth is that Peter Pettigrew, who was friends with all three, actually betrayed James and Lily and worked for Voldemort. When the year draws to a close, Harry and Sirius come face to face, flanked by Ron, Hermione, and Lupin, and a shocking realization comes to light.

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