[1] Larson has written for several animated series, including Foster's Home for Imaginary Friends, My Gym Partner's a Monkey, Growing Up Creepie, Gravity Falls, Littlest Pet Shop, and most notably My Little Pony: Friendship Is Magic.

Larson had become interested in My Little Pony: Friendship Is Magic from previously working with Lauren Faust, the series' original showrunner, on Foster's Home; he was surprised by her characterization of the main characters and started writing for the show.

Inspired by this analysis, Larson revamped his work over a six-year period to target a slightly older audience with scarier elements and with less humor.

[2] The resulting book became Pennyroyal Academy, which centers on school for budding princesses and knights that train to fight approaching armies led by evil witches.

[4] Prior to publication, the work was picked up by Reese Witherspoon's production company, Pacific Standard, for a film adaption.