Marceline was an absolute handful/the hardest for the company to make. They accidentally made her parts too big, but they actually had a spare huge Endoskeleton for her, so it was fine. They couldn't decide on an outfit for her, so they used a night guard outfit for her, both the company and Marceline herself actually liked the look of the night guard outfit on her. In some cases Marceline would have big freak outs and raging fits, doing extra damage since she's the strongest of the bunch, because of what the old manager used to do to them. Some of the employees and even Marilyn and Maxwell (if they weren't busy with customers) would hold her down and calm her the best they could, that usually worked. She was always the manager's least favorite.