Not to disagree - but the first thought I had, reading your post, is that maybe there is always a degree of risk that what one participant finds compelling, another will find either (in one direction) a bit flat, or (in the other direction) a bit over the top?
The second thing I thought of, because it involves
a brother refusing to help, was this from a Burning Wheel game where I was the player:
The backstory that was already established prior to this episode of play included that Rufus, my PC's brother, was still living at the ancestral estate:
Thurgon’s father is deceased, but his mother Xanthippe (now 61 years old) still lives on the estate. So does his older brother Rufus (40 years old)., the 9th Count of Adir (although for the past 66 years that title has counted for little, having been usurped by others).
It was the GM who put an overlay on this of Rufus being cowed by a "master", as a type of elaboration on the state of things in Auxol. That didn't raise any issues for me - it's probably not the only thing that the GM might have done (and I don't know if he was drawing on some prep here, or just extemporising), but it definitely worked.
As you can read, the upshot of events was that Rufus said
no to requests for aid - both large (from Thurgon) and more prosaic (from Aramina). He didn't insist that Thurgon "break up with" Aramina (I use scare quotes because they're companions but not a couple), nor did anyone turn up armed and looking for a fight!
Part of what made it work, I think, is that the refusal of aid from Rufus didn't impede the trajectory of play, including the escalation of stakes between Thurgon and his family. The session went on like this:
And it's apparent, from this outcome, that the episode with Rufus did not just affirm a status quo, even though it ended with Rufus saying "no". It serves to establish that one part of liberating Auxol is going to have to be
either liberating Rufus from "the master", or else dealing with him in some other way.
In this way, even though the scene ended with a "no", it contributed fully, and with some complexity, to the rising conflict across a moral line.