The following are notes made while this was in development. They do not necessarily represent the current state of this ability.
Helen has spent considerable time learning how to use the force of Electricity to return life to the lifeless; she has managed this even with bodies that have been dead for multiple days. It was while researching this that she came up with Antigravity Science.
Gil also has some experience with revivification (which he learned from his father, who is truly expert in it), but he isn't quite as skilled at it as Helen is.