I'm embarrassed to admit that I've never read the source material! Even so, I found this fanfiction accessible. Thank you for sharing it.

Regarding your musing, on posting or not, in your author's note... I think that sibling relationships are very suitable gen subject matter. In this case, there is a tragedy in its intensity, and that tragedy closely resembles a trope often overused in romantic love stories, but that resemblance doesn't inherently negate its use in gen -- especially when grappling with canon.