Must be hard for your mate.
My first dog was brought into the house under the cover of darkness and spent two days in my locker.
I got to keep him in the end, my mother said she never seen my room so clean and if I kept it up the dog could stay.
Tell him as from today to refuse food, dont wash, dont change his jocks, dont talk to anyone, stay out late, drink, mind you if he is a young lad he is doing this anyway
Good luck.