Grey is one of the playable characters in Mega Man ZX Advent. He is the Biomatch for Biometal Model A.
Grey's personality is influenced by his experiences over the course of the game. Being rescued by people who didn't know him, Grey is inspired by this act of kindness to do the same for others, even if they are enemies; Grey openly demonstrates this with his willingness to save the Raiders from an attack by Atlas. Another influence comes from Aile's advice, which encourages Grey to leave his past behind him and focus on making his own future. Because he has no experience interacting with others, Grey has no insight on proper mannerisms (as noted by the Sage Trinity as well as Aile), which makes him seem a little rude at times. Model A in particular describes Grey as "a tough-talking stubborn kid" and "a kind, crazy fool". Despite being paired with Model A, Grey is somewhat like Model X due to the fact they both believe that there shouldn't be a reason to save innocent people. He never smiles throughout the game until the ending of the game.
Because of the premature end of his brainwashing as a result of the Maverick ambush at the Mysterious Lab, Grey spent most of the game with amnesia.