i do enjoy the idea of krisnix even though i pretty much only ship them as exes (they have the divorce energy ever, it's amazing thank you capcom) because on one hand it's hilarious. i love the idea of the passive-aggression and continuous attempts to mildly inconvinience the other in the worst ways while also appearing sweet and caring towards the other because they still have to pretend. they make everyone around them miserable and it's really funny. on the other hand, they are really tragic if you think about them too deeply (and not only in a ship sense, canonically i find them to be tragic as well) after all, phoenix did believe kristoph was genuine at first, imagine how important and touching it must've been for someone who so strongly believed and fought for the people around them (his clients, his friends) even if the whole world was telling him that it was wrong to finally have someone believe in him when the world turned their backs on him. i really don't think phoenix was suspicious of kristoph from the very beginning of their relationship because a) phoenix was very vulnerable at the time. he needed someone to believe in him and b) why wouldn't he trust him? he had no reason to suspect him, after all, phoenix would have done the same thing if someone else was in his position and he had reasons to think that something was wrong. maybe it's possible that he saw himself in kristoph, a seemingly kind lawyer who believed in him when no one else would. in my opinion, the one who was probably wary of kristoph from the very beginning was trucy (don't even get me started on that because when i start talking about trucy there's no off button you can press to stop me)
yes, phoenix started suspecting him during his investigation and through the years, and it's possible that he already knew that kristoph had something to do with his disbarment by the time the events of turnabout trump happened. while it's true that he kept kristoph close to keep an eye on him, i also think he also thought he could fix him. let's not forget that phoenix found out that kristoph was capable of murder with zak's death, not before. oh my god i can't stop thinking about that, about the moment phoenix realized that kristoph was way more dangerous and rotten than he thought he was.
additionally, i think kristoph had very complicated and mixed feelings about phoenix. after all, no matter how much you hate someone, 7 years of (albeit fake) friendship is a pretty long time, and i don't see kristoph as an emotionless person incapable of caring about others, but rather as someone who did what he did in spite of his feelings towards others. he was driven by fear and that's one of the most powerful emotions, after all.
this rant started with me talking about how funny the idea of krisnix is and it ended up with me sobbing about how sad their relationship is in canon waaaah sorry but i love 2 fucked up men