We don't talk enough about what the creativitwins dynamic implies for prinxeity.
You are Roman Sanders. You were taught that world is in black and white. That there are things that you are and things that you must never become. These things are shaped like your brother. He is bad, and as long as you are not like him, you know you are good. You name him and his freinds the dark sides because they are evil and secret and need to stay that way.
And then one dark side comes along and he's everything you expected. Brash and mean and antagonistic above all. Every time Anxiety sinks out you imagine him going back to the others, to your other, laughing and sneering and boiling your blood. They will not get what they want with Thomas, you vow. You will save him, because you are his hero. So you poke and you make fun and you push Anxiety away.
Finally he leaves one day but suddenly without this "bad guy", without this "dark side", Thomas isn't Thomas at all. And you realize that you have been the bad one all along, not the hero, but the bully, and where this emo with dark clothes stands you have been seeing only your brother. And like your brother does, it brought out the worst in you. Anxiety makes Thomas better. He rescues you. You realize he doesn't want to be the bad guy, and you know exactly how that feels, you've seen how close you can get to the things you don't want to be. So you let up, give him the space to back away from the edge, and now he is Virgil. Now he is your friend.
And then, later, when the very person who defines good itself, the person who made you this way in the first place, abandons you, only Virgil is there. He sees what you see. The others don't know the dark sides like he does, like you do. They don't know how easy it is to become the bad guy, how close Thomas is getting to the things that are Evil and Wrong. You've been that close to the dark, stood face to face with it but you rejected it and Virgil rejected it too. You are both better for it, both proud of who you have become. And it wasn't for nothing. It can't be.
You are Thomas' hero even if he doesn't remember. Virgil rescued you when you were lowest and together the two of you will rescue Thomas too. He can reject the dark, like you did. He can be better. He can be Good.