Looking for a kinda Severitus

I'm looking for a fic that I think it's kinda Severitus. Harry's hit by a curse along with Snape. Snape is kinda his master and when Harry disobeys he has to punish him physically. They're both very distressed by it but they have to do it until Snape finds a cure for the curse. I want to read it again but I can't find it for the life of me!