Meltdown

Zeo's attempts to make a "cool guy" with "epic powers" didn't totally pan out like he was hoping, due to a machine malfunction and general incompetence acting in tandem.

What he managed to create was a sort of gross quivering mass of black sludge that mostly just kind of sucked and that everyone agreed was "the worst thing literally I've ever seen". They were going to destroy it, but then it started moving, and making these pathetic, flailing attempts to turn itself body-shaped, and... talking...

And then it started feeling a little unethical to drop it into the incinerator death chute so they just sort of let it hang out. Turns out she's actually kinda chill and pretty good at video games so it all worked out in the end!!! And over time she managed to build a form for herself that was relatively easy to hold together, though she still dissolves into goo whenever she gets a little too stressed out. And she does leave trails of menacing ooze behind her like a snail made of crude oil. But that's fine.