Lemon is a robot therapist, first appearing after Roko's accident with Crushbot. She helps Roko come to terms with destruction of her body inside the Bodyhub. Lemon is one of Melon's sisters. Lemon greeted Roko in her new body.
As part of her job, Lemon counsels nuclear reactors and dark matter detectors. Counseling of AI in nuclear weaponry have been previously mentioned in Number 1001: I Can Has CatPuter?.
Melon, Lemon, and Arthur roleplay as time traveling spies.