Armitage, aged 35, is Zimmer's imposing bodyguard and is a particularly quiet individual. He will defend Zimmer to the death. Of course, this is because Armitage is actually an android, or synth, much like the replicant. Armitage has the same schedule as Zimmer; he sleeps in the same room and eats the same food - not because he has to, but because he has been programmed to replicate human behavior as closely as possible.
Seemingly human, Armitage is in fact one of Dr. Zimmer's many androids, created in 2242 at the Institute in the Commonwealth, a region to the north of the Capital Wasteland that was once the New England Commonwealth. His true identity can be revealed in a conversation with Zimmer or by killing him in which Armitage drops an Android component.