whumpee and whumper who are both rich people with fancy title and some big castles or whatever,
they start fighting as training first, with wooden swords and big grins, trying to land a hit for bragging rights
but then whumper starts enjoying seeing bruises on whumpee the next morning, they try to land a few good hits in where they know they can catch a peek at dark bruises later
but after a while that isn't enough either, so carefully, weighing their words to try not to scare whumpee off, they explain their... interest in trying something new
and whumpee, with the usual big grin and fire in their eyes, agrees somehow, says they wouldn't turn down a challenge, that they'll see what whumper can dish out
somehow this is their new normal, whumpee either pinned down or restrained in some way (they find they both like the fight, the all out struggle for power, and whumpee loves the rare times they win and get to be a shithead about it, almost as much as whumper loves letting their parner win and hearing them get all proud), getting a new type of scar every time, the clean lines of a blade, the tearing of any decently sharp object, the lash marks from a whip, or even the rope burn all over them.
this is good, their arrangement is the best thing to have happened to both of them
and then, the dreaded day, whumpee has to take over the family estate. they've got a partner liked up for marriage and everything, and just like that it's all over. whumpee can't have those type of marks on them when they're married, they can't sneak off for days to see whumper when they've got responsibilities now!
whumper begs to find an alternative, to call the whole thing off, to bring in a new heir, to at least take them to whumpee's side too. anything, anything if they can keep seeing each other. even if their ..."relations" have to stop, they can't be alone anymore.
but whumpee is firm, there is no way. it's over.
so barely days later, at the event whumper wasn't even allowed to show up for (something about "causing a scene") guests wait with baited breath for whumpee who'll never show up
and a few days travel away, in a somewhat smaller castle, an ex-noble wakes up chained to a wall in a candle lit dungeon