If one's a nerd, growing up is supposed to be a good thing. One gets to finally leave behind those difficult teenage years: the crying jags, the freakish bodily changes, the days of writing bad poetry and brooding to the sounds of the Cure, Metallica and Sergei Prokofiev's "Violin Sonata No. 1 in f minor." One can also abandon that haunting sense of alienation, that feeling -- half self-loathing and half self-aggrandizement -- that no one can understand the misfit pain of being so different, so weird . . . and (one's unconscious whispers) so special. It can all be forgotten -- unless one is a Marvel Comics X-Man, a mutant whose strange and staggering powers are feared by the rest of society.