 When hunting humans, Predators normally avoid certain individuals such as children and some adults if they are unarmed, though they will spare armed ones if they happen to be pregnant or sickly unless they are attacked by them.A human who has managed to kill a Predator or a Xenomorph in single combat or has fought alongside a Predator is usually spared by the deceased hunter's comrades and given a gift (often a rare or exotic weapon) as a sign of respect.A learner's first successful Alien hunt is completed with the marking of his helmet and forehead with the acidic blood of his kill.