You became addicted to gambling.
You suffered a major financial loss, losing almost everything.
You made an enemy, people in positions of power, the authorities. They make you shouty-angry. They have military connections. Your rivalry grew into something stronger.
Imprisoned for a crime I committed
Cleaned out by a bad run at the gambling tables, in desperation you attempted a robbery of a money-changer's coffers, but were caught and jailed by haughty Avoirdupois knights. They've had it out for you ever since.
A serious relationship ended when your partner died, dying under mysterious circumstances.
Imprisoned for a crime I didn't commit
When the Cathedrale de Temoin was robbed a few years ago, those armor-plated Avoirdupois thugs threw you back in the gaol, demanding information on “your accomplices.” It took entirely too long for them to grudgingly admit you knew nothing about it and let you go.
You made a friend, a teacher, religious advisor or mentor. They are part of a tribe or other small group and can call on other members in need.
This is
Élan de Gauss. He's a member of a little klatsch of mages called the Tarot Club, who play cards and gossip and swap minutiae of arcane lore.