Monty was never really expecting to become a human. He'd literally lived his life as a crow, caged up in some witches house. And once these two dead boy detectives came into the house, he'd found himself a human instead. Though, unsure of his purpose. He was forced into spying on the dead boy detectives and being the 'revenge plan' for the witch. Though, maybe he did get a bit side tracked by good looks and such.
Monty had been technically helping them out, but also had been making things worse for them. Maybe it was anger of rejection from one of those dead boy detectives, Edwin. Maybe it was just because realization hit him on what he was made a human for. But these acts of sabotage caused the need for more help for the dead boy detectives and their two living additions.
Monty was still very sour acting towards Edwin, but still did things with the detectives regardless, just to seem less suspicious to them all. Though as he was walking to where the detectives all stayed and had their little 'meetings' there was a new face in the room. Monty hadn't met the mysterious male in the room before.