Fred and Friday have been the best of friends since they first met, that very encounter that changed Fred's life by gaining absolute control of "the Annihilator 9-0-9-0-9-0-niner" that was supposed to be Agent Brains's. He lives with Fred at his house that became also home, on which he will spend most of his time hiding and doing fun times with Fred.
Friday was sent to Earth by the Super Commander to become Agent Brains's robot partner in protecting planet from aliens. Friday and Brains are good friends especially if is a common interest even helping Braianna with her to trap and in the fred chase , sometimes he would go to her instead of Fred for help. Brains would really help him out, after all he is her robot, not Fred's.
Friday is half-jealous and half-suspicious of Borgolon to both his form and actions. For him having a pet in the same roof would mean less attention to himself and more to the puppy, if things got more complicated, he would just run away for a while and return for worries' sake.