WARNING! My comment has SPOILERS!
Maybe this is controversal but POOR LOUHI! Like yeah he was too selfish and self serving to live but I still wish he could have had a happier life even if it was in isolation. Considering the fact that his parents didn't die even when his powers manifested, he could have lived in isolation and still received love from at least his family.
He's almost 300 years old and has lived to grow too attached, get insulted, lose said person and then repeat the cycle for over 2 centuries. He's not considering the maggots and parasites to be his friends cause he loves his diseases. It's because they're the only things that actually STAY with him.
I really enjoy him as a yandere. His manipulative, victim card playing ass still tugged on my heart strings like no other. He could have been so much worse, a real plague but he does (somewhat) try to keep his effect to a minimum.
I can't help but imagine a AU where he stays rotting in isolation after his powers manifest out of guilt and terror of what he could possibly do to patients he so desperatly wanted to help. And just as he's mind is crumbling, his will power breaking, a random upir stumbles upon him. A new MC. (From what I understand upirs can't get infected)
Or a alternate ending to this game. Where after Louhi kills Abram and the body is dragged into the room, MC grabs the bomb and hides it on their body. They sit Louhi down and ask him if he really will continue caring for patients the same way he did for them. Of course he'll say yes and MC just follows up with. "How is that fair to me? Aren't I your fiancee? How is it fair that I have to succumb to your illness and move on while knowing you're going to continue on without me? You might even forget me one day."
I'm sure he would try to reassure MC or even make excuses but all MC does is kiss him before saying "I don't believe you but I love you. So just as I accept you and the disease you've passed to me. Please accept the gift I have for you." Bomb revealed right before it explodes. Just like in the game Louhil survives but he's so heartbroken and shocked along with the aftereffects of the bomb that he's killed by Abram's friends.
This is stupidly long but I hope this shows how much I love Louhil! I'm a yandere sucker and one that thrives off taking care of me while I laze around? Sign me up! (I can only wish that I'm immune or he migrates the symptoms for as long as possible lol)