Slightly different to mine.
The standard background .. middle son from a noble family, given over to the brotherhood at 10 or so, rigorous training, and a fairly decent end result. One of his early charges (say within a couple of years of becoming a full brother) is an arrogant, obnoxious prick of a noble brat. The kind that can make enemies simply by sitting quietly in the next room
Eventually he pisses off the wrong person badly enough that a contract is put out on him. My Casseiline stops one or two 'accidental' encounters, so the gloves come off with a full scale assault. He fights, kills a bunch, but eventually falls, and the noble brat is killed, probably in a pretty bad way. When the resulting carnage is found, my character is still somehow clinging to life. He should by all rights be dead, and its months before he can even rise from a sick bed.
The brats father wants his head, wants someone blamed for his sons death, and even though my character did his best, political pressure sees him cast out of the order in disgrace. Continued pressure from the noble means that he can't find any other jobs, and drifting downwards through society, he ends up in the Night Court.
He's torn at this point. Part of him wants to hold to his oaths. Though released from his vows when cast out of the order, they're all he has known for his formative years, and they mean something to him still. Another part of him wants to throw it all away. If this is his reward for faith and honour, why bother?
Thats kinda what I have in mind.