Long overdue, the Monty (and Bonnie, technically) doodle sheet it here, and I'm back with my FNaF headcanons) Don't confuse them with actual developers' canon, we don't know what could they improvise to answer our questions. Or maybe they'll raise new ones instead.

Let's say I consider Glamrock Bonnie and Monty best friends among the advanced animatronics showcased in Security Breach, and it was painful for Monty to have to kill his superior (basically, Bonnie, being an older model, taught Monty many things) buddy corrupted by the Afton code/Glitchtrap virus, the first step to the breakdown that led Monty to the maniacal behavior that we saw in the game... shame that we still have to come up with these backstories ourselves)