"Heero loves you Duo, but if he feels like control is slipping, he comes to me and I help him find balance again. Of course, over this last year, going between you and me caused him more guilt. As I said, he loves you, but he has come to love me in a different sort of way and now feels like he's cheating whenever with one of us. Such a complicated man.
So we came up with a solution. A threesome. He doesn't mind. I don't mind. The only obstacle is you and I am going to make sure you aren't. I'm going to show you everything I have ever learned and you will beg me before the night is through. I promise. For Heero's sake."
All through her speech I listened intently. My feelings bounced between nausea at what her foster father had done, anger at the acceptance of it, horror at Heero state, surprise he had never gone to any of the pilots for help, joy that Heero loved me, and fear of the future. Bound as I was, there was no way to stop Relena from doing whatever she wanted.
Duo agrees to be tied up by Heero, but has no idea what his lover - or his lover's other lover - has planned for him.
My notes: This fic has never heard of safe, sane or consensual. But it's fucking hot as hell. CW for completely nonconsensual BDSM that still works for me because I don't really expect anyone who's been through everything those three have to be completely sane or know what safe looks like. This is just... lovely smut, originally from the Boys in Chains Archive.