Assassins don't kiss?

When your friend and student Killua gets injured you take him home to his family. Unfortunately, even though Illumi tries to convince them otherwise, you're seen as a trespasser who needs to get punished. The punishment: Spanking - by Illumi.
He's always been perfectly polite the times you've met before, so how bad can it be?
⚠️WARNINGS! DUB CON, NON-CON, EXPLICIT ROUGH SEX, SPANKING, HINTED ABUSE ⚠️
The smutty part starts in Chapter 2...

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Making the decision for you he sat down on a sturdy wooden chair and patted his lap. Face full of doubt, feeling like a mouse willingly strolling up to a cat, you went up to him and settled yourself belly down over his legs.
'This is bloody humiliating,' you muttered as he placed a hand at the small of your back, efficiently holding you in place. If you hadn't been trapped before, you sure were now.