I think your right, I just Google search it and it said "trauma, nightmares, flashbacks etc" he did have flashbacks of how Harry gat accident and there's a bird there that looks like the bird that he saw and probably hallucinating it.. and I think that Felix is experimenting him right now through recording voice of felic himself so he could see the progress*? Felix is a pretty bad man, I tell you.. (⌒▽⌒)
oof, I didn't press the "plus sign". We pretty much said the same thing lol ╮(￣▽￣)╭
You know if the first theory is true then that could mean that Harry got into the accident on purpose to cause Felix’s ptsd.
I think Felix might have ptsd or some kind of mental disorder that Harry is researching or is simply interested in. Maybe he’s so excited about Felix’s paintings because he wants to know how it affects his art. I also think Felix is hallucinating the birdman and the homeless twins and that’s why Harry tells him to record instead of take a picture, so he doesn’t realize it.
My other idea is that Harry’s just simply interested in Felix’s paintings and wants him to succeed and continue making art, so he doesn’t want him to realize his delusions. Or something like that.