Your father is dead. Your Mom was still around, but she was always distant, more involved in her work than the family. You felt like a single parent, now, looking after your kid sisters and brother. The area you lived in was peaceful - small, not much nightlife but not much gang activity either. There were a couple of capes, jokes really, but nothing serious - and no supervillains.
And then the local gang recruited a Tinker, somehow. Or she recruited them, perhaps. You don't know what her specialty is, but she makes them guns. Lots of guns. Little guns you can smuggle into school; big guns that can wreck an entire house if you offend them. Guns that do horrible things to a person, alter them, torture them, freeze parts of them.
You were walking your brother home from school when some guys start catcalling you. When you flipped them off, they pulled out what looks like a miniature grenade launcher. You bolt, dragging your kid brother behind you, and one of them starts yelling and fires a shot. Part of the ground turns to glass, and it takes half your brother with it. You keep running.
You trigger when the next shot clips your ankle and you fall to the ground.