Urdnot Wrex is a mercenary and a bounty hunter who wandered around the galaxy for 300 years. With his father's betrayal Wrex's eyes were open to the truth about his people: most krogan would rather die in battle than try to rebuild their society. The once courageous and honorable warriors have been reduced to inflicting pointless violence. He turned his back on the rest of the krogan and left.
Even after many travels, there is little in the galaxy that can still surprise him. Despite his brutish appearance, Wrex rarely loses his temper. But when his fury is unleashed, it is a terrifying sight. He doesn't speak often, but when he does his words are direct and often shockeningly blunt.
Wrex didn't have any respect for Alice when they first met. But after countless battles, they warmed up and eventually became good friends. Wrex taught her honesty.