Here's twilight having, working with and learning about all things Zebras plus some adjacent lores at the same time. I remember some writers once saying how Zecora was supposed to be kind of secondary mentor to Twi thorough the series, and I wanted to lean on that. Plus, them being friends makes sense, Twilight is the pony Zecora interacts the most besides Apple Bloom and they have some intersecting interests. Twilight is a unicorn here because I felt this scenario would make more sense if it happened relatively early in her stay in Ponyville.