Maxence

Bebop and Rocksteady also appear (first in human form) in the IDW comics, where they also work for the Shredder and the Foot Clan. In their first appearance they were helping the mutant Alopex, find the secret hiding place of the turtles, but by the distrust of Raphael they were eventually thwarted. Finally, both voluntarily adhere to the transformation to their mutant forms, in order to join the ranks of the Foot

Their origin was finally explained in their villain micro. Rocksteady was a gang member. After he and his buddy Bebop were kicked out of their gang they joined the Foot Clan and defeated a bunch of other gang members for the honor to become mutants. Rocksteady became a Rhino while Bebop became a warthog. After screwing up a job and thinking Karai to be dead Rocksteady suggests that since Karai is dead, they return to Foot HQ and just say that she deserted. Karai isn't dead, however, and has overheard the entire mutinous conversation. She sends a bunch of Foot Ninja to kill them. However Rocksteady and Bebop defeated them and ask for a second chance. Karai than decided to keep them due to their brute strength.

Appearances

 * Teenage Mutant Ninja Turtles Micro-Series issue 1
 * Teenage Mutant Ninja Turtles Micro-Series: Villains issue 4
 * Teenage Mutant Ninja Turtles issue 25 (IDW)
 * Teenage Mutant Ninja Turtles Micro-Series: Villains issue 7
 * Teenage Mutant Ninja Turtles issue 27 (IDW)