Responses
Well, if you look at it from an mmo perspective, I think that makes m-21 the tank
He seems more of a Mana sink to me, he gets beaten more times then he wins or gets beaten and bruised up then wins. Tanks are usually powerful and are hard hitters as well as damage takers.
M-21, I feel, takes the most damage (from all the modified humans, excluding franky) and has such misfortune.