A quick one-scene fanfic (I know, holy crap) set post-canon, because I cannot reconcile any vision of the future where Zuko is not a huge tsundere masochist.
Who is abusing our lovely prince? Well... that's up to you. I think it sounds more like Mai than anybody else, but I deliberately threw in hints for at least four or five other characters. I really don't know, and that's the point.
The rest of it is deliberately ambiguous too - like what tools have been used, the exact nature of the sexual contact - and I rather enjoyed that. It's a nice counterpoint to drawn porn, where there's not all that much you can leave up to implication. Basically I'm hoping I can poke your imagination and make it fill in the blanks.
Written in first-person purely to leave the gender of his partner ambiguous (stupid English, not having gender-neutral pronouns), not because HAY GUYS IT'S MY OC NOTE THE DIFFERENCES. Still not sure about the perspective shift - I think it just means that whoever is topping on him understands exactly how wretched he feels, but I can't deny that it does read in a slightly unnatural fashion. Not helped by recollections that call for past tense.
Anyway I should stop over-analysing my own work and just leave you to it. Feel free to tell me who you think is being Zuzu's dom, because I'm quite interested.