Does anyone know of any TMNT 2012 fan fiction where Baxter joins the Turtles?

I'm not sure, but you could try searching on fan fiction websites like Archive of Our Own or FanFiction.net to see if there are any stories that fit that description. You could also try asking in TMNT fan communities or forums to see if anyone knows of any fan fiction that fits your criteria.

- Baxter's Redemption by DarkShadowNinja1
- The Price of Redemption by TurtleShell
- The Fugitive by newfangled
- Baxter's Tale by TMNT4ever
- The Lost Son by Leo4Ever
- The Mutant's Shadow by TurtleMaster93
- Baxter Stockman: Mutant of Science by ProfessorBaxter
- The Prodigal Mutant by TMNTWriter
- The Mutant Alliance by TurtlesUnited
- Second Chances by TMNTLover2012