Fantastic Beasts Spoilers!
The concept of an obscurus casts much of the Harry Potter series into a new light. I know I wasn’t the only person to think of Ariana Dumbledore. But what about Harry himself?
Like Credence, Harry is raised by a horrible family that hates everything to do with magic. They aren’t quite as extreme – they pretend it doesn’t exist instead of fighting it openly – but they punished Harry harshly for his childhood outbursts of magic. As a child raised in the muggle world, he would have had no idea that there were others like him, or that he would be able to leave the Dursleys for Hogwarts once he turned eleven. He would only have known that the strange things he could do made Uncle Vernon and Aunt Petunia very angry, and that they obviously thought there was something wrong with him. Harry could easily have suppressed his magic and let it destroy him from within, just like Credence. Yet he obviously never develops an obscurus, and I think the answer to why he doesn’t is the same thing that protects him throughout the series: his mother’s love.
Lily Potter’s love does so much to protect Harry in very literal ways. It shields him from Voldemort’s attempt to kill him and burns Quirrell when he tries to harm him. Lily’s love for Harry temporarily defeated the most powerful dark wizard of all time. It’s not that hard to believe, at least for me, that it also prevented an obscurus from forming within him, no matter how badly he was treated by the Dursleys.