Following the arrest of Heinz Doofenshmirtz for his crimes against humanity in the Tri-State Area, Carl (who was previously enslaved) returned to his duty serving for Major Monogram. Just like his counterpart, he can be a bit annoying.
He first appeared in Candace's mirror when she was contacting Monogram. He later appears again when Candace contacted Monogram again, this time about the Platyborg's kidnapping.
Monogram and Carl then bring in Doofenshmirtz for questioning regarding to the missing agents (who are captured and turned into cyborgs by Doofenshmirtz's wife Charlene).