Born to the Ylissean royal family, Lissa is the youngest of the three siblings, thus is the princess of Ylisse. Lissa's father, the previous Exalt, passed away when Lissa was about four years old and Emmeryn, her elder sister, succeeded him. Due to tensions left behind by her father's crusade against the neighboring country of Plegia, Lissa's older brother Chrom formed the Shepherds to defend Ylisse's boarders from Plegian bandits. Lissa joined as one of the vigilante group's healers.

During her youth, she met Maribelle, a Ylissean noble who was scorned by noble youths due to her haughty attitude. Seeing past her prickly exterior, the two quickly struck up a strong friendship and they consider each other their best friends, so much so that Maribelle would join the Shepherds herself to be with her friend.

In the future, should she be paired with a member of the Shepherds, she will be the mother of Owain. If she marries Robin, she can be the mother of Morgan.