Doing Step Bro Together, Mackenzie Moss and her BFF Lacy Lennon do everything together. Everything. Brad Sterling, Mackenzie’s stepbrother, has really started to wonder how far down the rabbit hole Lacy and Mackenzie have gone. At the same time, he has the total hots for Lacy. Mackenzie notices Brad checking Lacy out beneath the miniskirt of her school uniform. She calls him on it, but doesn’t pursue it because the girls decide they need to go shower together. Brad can’t believe they possibly do even that together, so he decides to spy on them.