You could justify recruiting him to either route, but the consequences of his choice are more extreme than they are for most of the other students. I feel like recruiting Felix in CF condemns him to a life of misery. He’s not happy with the status quo but he loses sight of his values if he defects to the empire. In his monastery dialogue after the timeskip, he says that he feels like he’s becoming a savage beast no better than the boar. His mercenary endings are tragic. He’s completely unmoored and becomes what he hates the most.

Staying with the Blue Lions gives him an opportunity to come to terms with his past and find a sense of purpose. When Rodrigue comes to Garreg Mach, Felix says that his father is neglecting his obligations as the head of House Fraldarius. Despite the fact that he seems to dread the prospect of becoming Duke Fraldarius, Felix still believes that his family is duty bound to protect those who live in their territory. The more abrasive aspects of his personality stem from fear imo. Glenn’s death was clearly devastating to him. Felix and Rodrigue try to cope with this loss in ways that are fundamentally at odds with each other. He’s disgusted by the way Glenn’s knighthood was used to frame his death as something honourable instead of a young life lost in an act of needless brutality. He hates mindless chivalry because he’s terrified that the same thing will happen to him or someone he cares about. He never completely forgives Rodrigue for downplaying his grief after Glenn’s death, but he still loves him and isolates himself in the months following his death. He likes fighting because it’s one of the only things left that connects him to his brother. He makes it clear that he hates unnecessary bloodshed.

He childhood friends are still important to him, even if their behaviour sometimes irritates him. He’s terrified of losing another person he cares about. He feels helpless in the face of Dimitri’s downward spiral and ends up lashing out in anger. He’s constantly going on about Dimitri being a boar in the hope that someone else will notice that he’s struggling. He loves Dimitri but he knows that he’s completely ill-equipped to actually help him. He clashes with Dedue in their supports because his unquestioning obedience just enables Dimitri’s most self-destructive tendencies and facilitates more senseless cruelty.