At best, Tyson is - usually - content with his place in the world.
He hates himself, he hates the work that he does and knows that he isn’t getting a happy ending in this lifetime, but he is content to shoulder that burden, because Tyson loves the Moriarty Mirrors and he will sacrifice everything for those he loves. Especially himself.
Tyson doesn’t know what to do with happiness. Not truly. There are times when he is happy, naturally, but once he realises that he’s happy, Tyson will go out of his way to distance himself from it. To run away from it. Unless he’s already in too deep to avoid further damage. He has to be eased into happiness, like a turtle in a cooking pot.
A stupid, stupid turtle in a pot that could never hurt him. The idiot.
He thinks that he doesn’t deserve happiness. Afraid that he’ll break it, that it will shatter under his fingertips and hurt those he cares about. Tyson simply does not get nice things; not unless they were going to be ripped away from him. He would rather hurt himself now, to avoid later pain.
Tyson would rather distance himself - shove people away, snarl words that he doesn’t mean with a vitriol only ever meant for himself - than risk hurting someone else by being their bad luck charm. Happiness is overwhelming for Tyson and he doesn’t know to how to accept it without fear, without guilt.
This is most commonly overruled by Tyson’s loyalty. He is loyal to a fault. No matter how much it hurts him, he won’t abandon those he cares about. Once Tyson cares, no matter how afraid he is, he can’t abandon someone; even if he tries to distance himself, Tyson can’t stay away completely.
To Tyson, that is a sign of weakness. That he is being selfish and even more ‘proof’ that he doesn’t deserve that happiness in the first place, because Tyson isn’t a good person, he’s dangerous and being around people puts them at risk. He doesn’t want to put innocent people in the crosshairs.
Staying is a sign of weakness and proves he doesn’t deserve that happiness, whereas running shows that he’s too weak to have earnt that happiness; too weak to deserve it. It’s a no-win scenario. Whatever action Tyson takes, he will convince himself that he’s being a coward.