mind_writing here is the answer to your question: if Logan had yandere like feelings for a side, who would it be?

I think it could be any one of the other core four. Here's why:

Roman because Logan would misunderstand the idea of a grand gesture and assume that killing someone was grand enough (probably because of what Roman did in the Valentine's video) to get his attention and love. He'd think it was okay because he has no understanding of feelings and Roman's constant remarks of "kill the problem" might convince him that murder is an appropriate response to rivals, considering Roman is the side representative of Thomas's romanticism.

Patton because Logan wants to protect him. Logan would feel that Patton needs protecting and defending because everyone (excluding Virgil) has treated him like trash and he hasn't objected. He would think it's okay because Patton is easily proud of people, telling them that what they've done was a good effort even if it was a step in the wrong direction. Logan isn't morality, he doesn't understand that murder is morally wrong. He might believe he is fixing an issue because "murder is effective, it gets rid of the problem permanently and efficiently."

Virgil because Logan wants to convince him he won't get hurt. The mentality that "if I kill the person trying to take him from me, he'll be convinced that I'm going to keep him safe." Even though that idea is completely wrong. It may seem that way to Logan because he is constantly seeing Virgil get hurt so he would kill for him to make sure that Virgil's pain stops, probably causing him more pain in the process.

There are my arguments, feel free to debate with me on this.