Ethan Rom is one of The Others and grew up on the island as his parents were part of the Dharma Initiative. He poses as a crash survivor to infiltrate the group, checking on Claire's blood levels to monitor her pregnancy and going on hunting trips with Locke. But Hurley, who is putting together a census of the survivors, exposes that Ethan was not actually on the plane after Ethan says his last name is Rom and that he's from Canada. Ethan is actually a surgeon involved in The Others' research into the problems with pregnant women dying on the island, and he goes to great lengths -- sometimes by force -- to include survivors from the crash in this research.