So perhaps Cerebella's mom made Vice Versa specifically for her daughter, and Cere appears to be an expert at manipulating the living weapon. It implies Cerebella has had a lifetime of training to master Vice Versa and the gymnastic skill necessary to be an acrobat. But how did she end up with the mob?
Option 1: Tragedy
Cerebella's mother is dead. Cerebella lost everything. Homeless, Cerebella does strong-arm routines in the subway for spare change and commuter cash. Vitale notices and takes her under his wing. At first it is simply performing at the circus, but soon little favors are asked ("go with Beatrix and pick up a briefcase" "squeeze open this safe, I uh, forgot the combination" etc.) that slowly erode to some morally-questionable jobs. Next thing you know, she's an enforcer to the Medici mafia.
Option 2: Rebellion
Cerebella's mom is alive and annoyed her daughter literally ran away to join the circus. She's disappointed Cerebella threw away her gymnastics scholarship to New Meridian University for fame. Juggling elephants on the high-wire is impressive but there's something about the circus that seems a little shady...
Option 3: Family Business
A Living Weapon-smith for the Medici, Cerebella's mother becomes a target of rival gangs or even the Renoirs. With her parents murdered, Cerebella is taken in by Vitale. While browsing through her mother's stored Living Weapons in the armory, Cerebella discovers Vice Versa and her strong compatibility with it (remember, few people can actually use living weapons). From there she trains to better protect and serve her new family.
Option ∞: Anything's Possible
The real story isn't as maudlin and flat as the above theories, but you get the idea!
