Kaidan and Grief
I have always HC’d Kaidan as being very emotional and feeling things like anger, grief and loss intensely. Not because he’s an angry person, but because he *is* so emotional and he feels things deeply. When he lashed out at Vyrnnus defending Rahna - that was those emotions.
So for me, Kaidan is bitterly emotional after he loses Shepard over Alchera. Angry, despairing, unable at first to move past those horrible feelings. He doesn’t fall into drinking or drug use, but instead loses himselves in despair and functions on autopilot. Kaidan throws himself into his work with a desperate abandon that worries Anderson - it’s clear he doesn’t care if he lives or dies. He accumulates vast sums of credits from danger pay from taking on these missions. He gets new scars, new skills, maybe even a tattoo.
The bleeding wound that is the loss of Shepard never quite heals because what if? What if he’d disobeyed their orders and stayed? What if Joker hadn’t stayed behind? What if Shepard hadn’t gone back for him What if? WHAT IF?
After a time his life becomes more normal and the agony of missing Shepard isn’t quite as keen. So he tries to move on … but he never quite can. There is always a face in the crowd that looks like theirs, or that damned Shepard VI telling him he looks like a varren person, or their face on Memorial posters and Alliance advertising - “Remember Normandy”.
He can’t forget.
He hates it and loves it. The pain becomes something that he clings to desperately, bitterly, ferociously. Because it’s all he has left. The gap Shepard left in his life is one he doesn’t want to fill; he needs to feel something, even if it’s pain.