what about when Caregiver is a kid? Whumpee is being tortured by the Caretaker's parents, and when Mommy/Daddy/Gender-neutral-term-for-parent-that-ends-in-y isn't looking, passes them food or bandages? And at the same time Whumper is trying to teach Caretaker how to whump.
I've never thought of this before but I absolutely love it. Especially with Whumper trying to get the kid to follow in their footsteps. Maybe they turn Whumpee into a demonstration:
"Then point the blade like so..." Whumper made a show of angling the knife, making sure the kid noted everything from finger placement to grip strength. "And slice!"
Whumpee doesn't want to traumatise the kid further by screaming and crying — especially if Whumper makes the kid try some practical learning — but being stoic will just prolong the awfulness for everyone because Whumper is never satisfied until Whumpee is defeated and broken.
And the chances of the kid growing up to become a whumper themself is really high and really tragic. The more lessons Whumper gives on how to cause pain, the more distance is put between the kid and the instinct to heal. Young people are so impressionable and easily influenced in ways they don't even notice. They are as oblivious to becoming like their parent as they are obvious to growing taller. The change is always happening, but they don't realise if until one day they look at themself and realise oh. I didn't used to be like this.
But Whumpee sees the change from start to finish. It's almost more painful than the whump itself, watching as the kid's eyes turn from scared to desensitised and their hands swap plushies for knives. Whumpee can hear the screams of other captives suffering under their hand.
By all means, Kid is no different than Whumper now. They certainly view themself as the same. But, for some reason that they can't quite remember, Kid can never get themself to enter Whumpee's cell. The idea of hurting them just doesn't feel right. It doesn't feel wrong, either. But they just don't want to.
When Whumpee dies after years of captivity, Kid — who is well into adulthood now — finally goes into their cell to clear out the body. As they clean the blood off the floor from where Whumpee lay, a memory unearths itself from beneath decades of cruelty and being taught to hurt. A memory from their childhood, a time when the white cloth they held was a comfort blanket rather than a sheet to smother a corpse, and their eyes watered instead of sharpened at the sight of blood.
Are they able to push the memory back down again, or is the recollection of childish kindness going to eat them alive?