read this a long while ago

I think it was an infirmary teacher(seme) helps a student(uke) that was injured,student may have been from another school end up sleeping with him and then uke disappears Uke comes back years later but roles are reversed and the uke is now the seme. (uke had to move /different school or something) Someone comes in later to pick up seme as he ran away i think from body guards and claims he will return

It was a oneshot in a volume or scanned as a oneshot if i remember right

I'm don't think I know of the one you're specifically searching for, but I do know of similar one by Sakira if you're interested in reading more yaoi like that. It's Himura-sensei no Junan (or The Suffering of Dr. Himura) in Hatsujou Kareshi. The next chapter in that collection, chapter 8, is a sequel and her previous collection has a bonus about him, too.

Thank you for the suggestion for another one to read