Vault boy. That is an interesting choice.
Rumor has it he’s not winking coyly and giving a thumbs up of approval. He’s standing there with his outstretched arm measuring a fire ball from an explosion in the distance. One eye closed as not to get thrown off by his three dimensional vision that only works when he uses both eyes. And by the big smile we can deduct his thumb does indeed cover all of the fire ball, meaning it’s safe to breath the air where he is standing right now and he won’t die of toxic fumes.