God Eaters are humans who undergo intensive training to learn to control God Arcs, which they are paired to with Fenrir's "aptitude tests", and they use such formidable weapons to fight against the Aragami. They are humanity's last line of defense formed by Fenrir against these devourers of entirety. All branches of Fenrir divided God Eaters to each unit numbers, except Fenrir America Branch they are using NATO phonetic alphabet (as seen in Return of the Messiah) instead of numbers.