Twilight is a well-learned mage. She knows spells to keep the symptoms of being in heat in check, so that nopony even knows unless they already know her internal clock.
...of course, such a spell only works if she actually remembers to cast it. Ideally before hearing from petitioners in her court.
Good thing she can trust Spike to be her Number One Assistant in more than just library organization.

Written for a sort of Smaugust/NaNoWriMo combination thing. Today's prompt was "Seasonal," so Twilight is, uh, "in season."

Contains: dragon/pony sex, sex with a condom, doggystyle (ponystyle?), blowjob, accidental exhibitionism?