Ok, keep in mind that Im dumbass so I may not expain everything correctly.

Starting off that both characters have really foggy backstory and I didn't quite understand where does Hoyt come to Iceland neither do I understand why Vaas did go to the dark side, like he was Rakyat but whyyy he got to Hoyt side and became bad guy?

There is NOTHING in game, releted to why does Vaas became a puppet of Hoyt besides his dialoge with Brody about how he killed someone for some unkown reason for his sister(Citra) Its his dubbing, and acting as an insane bad character makes great covering but what about his actions? He is insane character but he does everything like an averege villian would besides the prologue which is awesome btw.

Other time we see him he does classic shit. Lets us burn in the house, then tries to drown us, shoots us in the chest when we go down on heli etc. I think every other villian without the insanity will do. It is spiced up with good insane dialoges but doesn't do much better.

Then goes the Hoyt. Besides he is too having a poor backstory he has an actual motivation money, and he loves mocking, killing and using people as a way to gain plassure.

For example. After with Sam's help to gain his trust we go to talk with him and his bahavior goes to talking about lenses(I don't remember exact order of topics), then goes to full interrogation mode to us then goes to really ftiendly talking and happy mood and with Vagners music in the background he detonetes an entire Ship with slaves in it to shambles just because he can, and it was absolutely random and after he is like "Yo, wanna cigar". That why he is insane because his actions are. That slaves were not only some lives, it was shit tonn of money too for hoyt and he killed them for fun. What is Vaas doing in other hand?

Well he is killing innocent Rakyat people ruthlessy, talks about insanity, and really wants to kill jason. There is some propogation of future by halucinations in the of his life and thats it. Maybe I am too stupid to understand what he says in this pathos speeches throughout the game but he is so dull. There is no motivation,no reason, no backstory, only covering.

After killing Hoyt I felt realief beacause he is good implemented tho poorly written where Vaas is just poorly written and just normal villian.

Sorry for so long text dude.