In "June 13 - Part 2", Angela realizes how Claire died: the newborn Nathan has the same power absorption abilities that his great-grandfather Arthur Petrelli and to a lesser extent his grand-uncle Peter had. While still an infant, he took Claire's powers which allowed her to die during childbirth. However, as Nathan can only keep one ability at a time, unlike his great-grandfather, he lost her abilities soon after her death when he took Hiro's power. Afterwards, Angela raises Claire's daughter Malina while Hiro raises Nathan himself.