I might be misremembering, but I'm remembering a comedy/romance fic that involved Chrysalis going on a date with a Celestia (principal or princess, not sure at this at this point), and the mane six and Luna are in the restaurant spying on the date basically doing sketch comedy. This might have been part of a multi-chapter fic or a series of fics.

Honestly at this point I might be merging fics together in my brain.

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Of Princesses and Changelings, or White on Black?

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Oh wait I found it. Principal of Equestria was it. Even has the extremely specific part of Chrysalis and Principal Celestia going on a date.