He is a professional assassin and he needs to do his job. He got a contract for Sophie. Financial or love reasons, or someone wanted to hurt her boyfriend - he didn't care. He discovered where Sophie was living, learned her habits.
That very night he was watching her coming home. He watched her get nailed by her black boyfriend, and when Sophie's boyfriend left, he came.
Once Sophie woke up and saw the gun, she understood.. She was begging for mercy, she promised to do anything he wanted. So.. Why can't he get some bonuses and enjoy his job?
Her round ass for her LIFE? Or just for extra 20 minutes?
Let's see and fuck that sweet asshole first!