Gerome is the son of Cherche from the future and a Wyvern Rider like his mother, his wyvern being in fact a future version of his mother's wyvern, Minerva. His birthday is September 1.
He thinks messing with the past is a bad idea and is antisocial towards everyone in the army, pushing them away when they try to approach him. He even acts coldly toward his own mother Cherche, whom he addresses by her given name. During their first meeting, he makes it clear that he does not want to become close with her.
Gerome was the one who made Lucina's mask which she used to disguise herself as Marth.
As a Wyvern Rider, Gerome can promote to a Wyvern Lord or a Griffon Rider.