"I know, I am angry too. I should've taken your underwear off *before* I tied you up. Oh well, that's why we have safety scissors..." (X-post /r/AnnoyedToBeBound)
Your new step-mother insists that the best way for you two to bond is to bathe together, "like a mother and son should". She wasn't wrong, and now you really are starting to get to know her better.