Nova is the daughter of Sans and Toriel all three love puns
She can summon Gaster Blasters with flames and Bones with flames in them also fire and teleporting like sans
Sans's brother is Papyrus who are skeletons
Toriel is the ex-queen of the Underground and ex-wife of King Asgore she had a son named Asriel and adoptive daughter named Chara until they were killed by humans
Gaster is sans and papyrus dad but was shattered across time and space by an experiment
Sans's left eye can glow blue/yellow