Littlepip was chosen as the Primarch of the XIII Legion by Empress Celestia shortly after the unification wars. She was chosen for her ability to devise diverse and easily adaptable combat plans, each of the Primarchs was given special genetic-enhancements, Littlepip's was increased cognitive capability and a greater understanding of military tactics, furthering her ability in combat. During the Black Heresy, Littlepip, along with the Primarch of the 1st Legion: Homage the Lion, and the Primarch of the 9th Legion: Morning Glory, created the Imperium Secundus, and after the Black Heresy she wrote the Codex Astartes, a grand book of battle doctrines which unfortunately has become outdated since her entombment in stasis, although ten-thousand years she rises once again thanks from Changeling intervention.