Kyoumaki: Kyouya makes a very grave mistake and (maybe not so) accidentally leaves his notebook in the Third Music Room or Tamaki's Room. Tamaki reads it to find out that Kyouya's been writing erotica about him, and decided to make Kyouya's fantasies come true.
Tamaki seme. Preferably with semi-cofused masturbation on Tamaki's part when reading, before the actual sex, and realization of internalized homoerotic tendencies.
Is that too specific? I'd love to see what someone would do with this.