When pressed for specific, evocative details of burying his wife, Gale unexpectedly expresses an intuitive empathy, asking Sayid if someone he was close to had died.
Lived in a cave for four (one of the Numbers) months -- a two day walk to where he was captured
Henry can hear through the door of the gun vault where he is being held making him aware of anything that has occured in the room outside. However he does not make an effort to draw attention when Mr. Eko came to the hatch.
Eko asks Gale for forgiveness for killing two of The Others his first night on the island. Eko apparantly believes Gale is one of the others.
Has begun an attempt to turn his captors against one another, namely Locke and Jack. He did this by giving Locke the feeling that Jack "calls the shots" and he is just playing along. Locke got angry enough about this to throw hatch inventory around which lead Mr. Gale to smile.
Someone on the Island refers to him as "my brother" [1], indicating that he might have a brother amongst the lostaways or The Others
THEORIES
We know that the writers have used pseudonyms for characters sent from the others to infiltrate the Flight 815 camps. The Oceanic Air website used the anagram "other man" in a puzzle to identify Ethan Rom. Could Henry Gale also be an anagram? Here are a few examples of what the anagram could be:
Anagram of his name... Angry Heel
Anagram of 'Henry Gale Minnesota'
See an Other man lying
Insanely Hatemonger
Gale has attempted to start a feud between Locke and Jack by telling Locke he appears to be in Jack's shadow. Later, Locke got angry enough to throw hatch inventory around just outside the armory where Gale is being held. Keep in mind however, that Locke knows Gale can hear what goes on just outside the door (he had just learned this). Perhaps Locke wants to make Gale think he has accomplished something.
Gale is the "he" that Zeke refers to when arguing with Ethan about the list.
Henry Gale is an evil genius and the leader of the others, which Mr. Eko somehow seems to sense as he apologizes to Gale for killing two others on his first night on the island.
