In the Crimes of Grindelwald trailers, there are clips of Credence apparently pushing away his obscurus – but as I said before, I don’t buy that it’s going to be that easy. I would guess that in this scene, he’s not permanently getting rid of the obscurus; he might be trying to, but I can’t imagine it will just let him go.
According to the first Fantastic Beasts movie, an obscurus is formed when a young witch or wizard tries to suppress their magic. Credence was brought up among fanatical witch-hunters, so he must have been terrified by the early signs of his powers. By the time of Fantastic Beasts, he’s bottled up his magic and no longer seems to be aware of it himself, except when it takes control and turns him into a dark cloud of anger. Obscurials become what they are out of self-preservation, but the obscurus is like a parasite that slowly destroys them.
How do you stop being an obscurial? It’s never been done before. Credence is the only one to even survive to adulthood. Clearly it’s not as easy as simply accepting your magic, because Credence spends most of Fantastic Beasts meeting with “Percival Graves” in secret and wanting to join the magical world. He asks “Graves” to teach him magic and doesn’t argue when “Graves” claims he’s “unteachable”. Simply deciding that Mary Lou is wrong about magic being evil does not get rid of the parasitic dark force inside of him. However, self-acceptance would have to be the first step, because if you’re still trying not to have magical powers, there’s no way you’re going to learn to control them.
By the end of Fantastic Beasts, Credence isn’t denying the existence of his powers. He’s embraced them, and he’s letting them control him. He’s overflowing with anger and not trying to reign it in at all – although I think it’s noteworthy that even in his obscurus form, he never harms Modesty and begins his transformation trying to protect her. The obscurus is all Credence’s anger and violent impulses running wild, but it’s not acting blindly or randomly.
Extreme denial followed by violent anger. That seems to be about as far as most obscurials get, but I wonder if we’re dealing with a Five Stages of Grief type of process. Credence, after the end of Fantastic Beasts, is clearly no longer a dark cloud of anger ripping up buildings and killing people, at least not at the moment. That potential is undoubtedly still inside of him, though. The feelings of fear and betrayal that led him to transform at the end of the movie would certainly not go away overnight. I don’t think a lifetime with the Second Salemers would either; he’s probably still not sure exactly how he feels about magic. There’s no one he can really trust or go to for support: Newt wanted to help him but now believes him to be dead, Percival Graves turned out to be Grindelwald, and his family drove him to become an obscurial in the first place. It looks from the trailers like he’s found a friend in Paris, but until they meet, he’s alone. In other words, he still has a lot of emotional trauma to work through.
The remaining stages of grief are bargaining, depression, and acceptance. It makes perfect sense that his storyline in Crimes of Grindelwald would explore these, especially the first two. He’s now aware of his place in the magical world and presumably doesn’t want to explode into an obscurus, but he won’t know how to go about learning to control his powers, and he may very well still have mixed feelings about doing so. “Please, don’t let me transform into that thing again, I’ll do anything to stay human …” “It feels so strange to hold a wand. What would my mother say if she knew?” “Can’t I just be normal? A normal muggle? A normal wizard? Anything but an obscurial?” That creeping realization that he might never be a normal wizard and will certainly never be a muggle, along with his extreme isolation, could make anyone feel depressed and hopeless. I wonder if the emotional struggle for him in this movie will be less about repressed anger lashing out and more about being tempted to just give up. To stop trying to control the obscurus, stop trying to find a place in magical society, and let the dark smoke loose again.
If I were going to come up with a “cure” for being an obscurial, I think I’d have it be casting a patronus. The patronus charm is powerful and difficult to cast, something that is not even usually taught at Hogwarts, so to be able to do it, from a purely technical standpoint, you would have to be in very good control of your magic. It’s rooted in your happiest memories, and one of its functions is as a magical protector. It can ward off dementors, which – much like obscuruses – are physical manifestations of people’s most dangerous and desperate negative emotions. There’s a difference, of course: an obscurus is a part of the person it’s formed in, while a dementor is an outside force. However, it doesn’t seem like too much of a stretch to say that an obscurial who gained enough control of both their magic and their emotions to cast a patronus would no longer be at risk of letting their obscurus control them, and that such a negative force would slowly fade away in a person who it no longer has power over.