Lucina is the daughter of Chrom, born sometime after the Plegia-Ylisse War and a few months before the Valmese invasion. Due to the death of her aunt Emmeryn, Chrom succeeded her as the new Exalt of Ylisse, making Lucina the Crown Princess. As proof of her heritage, she bears the Brand of the Exalt on her left eye.

In the original future, Lucina recounts that she spent a lot of time with Chrom, developing a particularly strong bond with him. She was taught swordplay from an early age by Chrom himself, of which she showed significant talent, and also his penchant for unintentionally destroying training dummies. Strong-willed and pragmatic, Lucina is determined to defy fate and alter the dark future she came from. She is primarily inspired by historical figures and her heritage. Marth in particular, whom she views as a beacon of hope, was the alias she chose for herself to give herself courage, and she tries to emulate. Bearing a keen resemblance to Marth, it even leads to her being mistaken as him by Tiki when she is introduced, with the latter remarking that her involuntary actions when helping others further liken her to Marth himself. Furthering that point, she even speaks in a very formal and polite manner, more reminiscent of him, contrasting her father. Despite the apocalyptic future, Lucina remained defiant against the Fell Dragon and was a rallying spirit for those who continued the fight against him. As the leader of the children of the Shepherds, she feels responsible for their lives for the sake of their mutual goals of saving the world and their parents.

Her biggest inspiration is her father Chrom, and her primary goal is to save him in particular, as it was his death that set the future on its dark path. For him, she will take drastic measures if it would save her father, as when she deduced her father's true killer, she took it upon herself to enact judgment on them for Chrom's sake. However, she ultimately respects his wishes when he opposes her decision. Regardless, Lucina adores her father, and the opportunity to encounter him once more was filled with pure joy and excitement to be with him in his prime. She has dark blue hair and dark blue eyes. She wields Falchion.