I know you already answered an ask about brushing at your fingers, but i need to know moreee
Ok, there is still nothing written, and I'm not entirely sure what kind of details you're looking for, so you're getting landed with Vibes.
So the part where I said River reacts violently to things - he straight disassociates and it's again a time warp for him. He remembers Before the Thing and he is with it Now, but DURING? Not so much. So he'll snap back to himself and have no idea what he's doing or where he is for a hot minute.
And it's not predictable, either. It's not like he figures out he doesn't like small spaces, or he's suddenly afraid of the dark, and can avoid them. And because he 'goes away' for whatever period of time, he doesn't even know what it was.
He actually does okay at first, because he's a little too wired and confused to pay attention to a lot of details. When he's arrested by the Dogs and they won't let Louisa go with him, and they're in the city, not a whole lot looks different, and his brain can sort of skip over things that Aren't Right. He's too busy trying to listen to Taverner and Lamb when he's being interviewed to really notice his reflection in the observation glass, but when he does, that's what really convinces him that he's been gone as long as they say. His hair is longer - like season 1/2 length. His face isn't rounded anymore, but all sharp and angled. His nose isn't quite straight anymore, and one of his eyes isn't blue anymore from some long healed injury, and when they take him to the infirmary (or hospital, haven't made up my mind yet), as he's being looked over, they're finding more and more evidence of long term torture, but nothing that seems recent. The injuries are more than a year old.
One of the biggest issues River has is that he has no idea if Frank is dead or alive. He has no idea what he was doing in London, he has no idea why he had a gun, nothing. The Park wants to know what Frank is planning, and River has absolutely no clue. They don't know if he was released as a strategy, or escaped, or was part of the Plot and is just playing them for fools, and all River knows is it's definitely not the last one.
As months go by, and River is slowly starting to navigate this new world of his, he does somehow get into a fight with Marcus. Not on purpose, it's an accident. Like someone says or does the wrong thing, and River Goes Away, and when he comes back to himself, he has Marcus on the ground, hands up in surrender, his face bloodied and bruised and looking like he's gone ten rounds with Rhonda Rousey and the first words out of his mouth are "What happened to you?"
And it turns out that not only is River's memory just gone from his time with Frank, it appears that he has new skills. Ones he didn't even know about.
Anyway - hopefully that helps a bit? Like I said, there's nothing written on this yes, and who knows when it will be, but very exciting to know that other people are interested in my fantastical daydreams