Anti-Mabel

"“You’re the Anti-Mabel!” -Mabel Pines"Anti-Mabel is one of the alternate universe versions of Mabel Pines trapped in MAB-3L. She pretends to be an ally of the main Mabel, before betraying her and revealing herself as the Anti-Mabel. She then would go on to pretend to be the Main Mabel in hopes of taking over the main dimension. Luckily, Main Mabel and the Mabel Army, alongside Stanley and Stanford, would defeat her and trap her in the vacuum of the Multiverse.

Getting Trapped
"“Unfortunately, we’re trapped here forever.”          -Explainbel"At some point before the Main Mabel ended up in MAB-3L, Anti-Mabel was trapped in MAB-3L as well. Little else is known about this.

Befriending the Main Mabel
"“Finally, a normal one.” -Mabel Pines"Anti-Mabel pretended to be waiting for the Stans as well, to trick Main Mabel into becoming friends with her. The two of them stole a flare from Military Expert Mabel, and set it off to get the attention of the Stans. Once the Stano landed, Anti-Mabel locked Main Mabel in the outhouse, and then revealed herself to her. Then, she impersonated Main Mabel and went onto the space ship with the Stans.

Fighting the Other Mabels
"“MABEL FIGHT!” -Table Mabel"The other Mabels would later use grappling hooks to catch up with the Stans. Anti-Mabel trapped all the other Mabels however. The only one she didn’t trap, Main Mabel, would get into a one on one fight with Anti-Mabel. The Stans, confused on who was who, remained neutral, until Main Mabel removed Anti-Mabel’s sweater, revealing that Anti-Mabel was wearing a shirt that said “I Hate Cats.” The Stans immediately knew which one was which after that, and they shot Anti-Mabel into the vacuum of space.