A short story beginning from a 4 AM scene: Sirius is awake and tortured by the knowledge that Remus means more to him than any friend. Finished.
Lily began a chain reaction when she offered Sirius some very interesting information - not intentionally, of course. RLSB.
Repost of the original A handful of scenes give shape to Remus and
Why it never really worked between Remus and Sirius.