Jean Grey's only weakness is that she cannot control her alter ego phoenix. Otherwise she is a substantially awesome superhero. (Wiki Answers)

I choose Jean Grey to best define me. Admittedly, the extent of my comic book super hero knowledge comes from my most excellent husband, popular film, and a bit of research. Right off the bat, I’ll make a risky choice by identifying with Marvel rather than DC.  Marvel heroes are flawed—more human—creating complex characters, waging battle within as often as they deliver the world from evil forces. (CBSS) Jean Grey’s “dark passenger,” as Dexter Morgan so aptly identifies it, is Phoenix.

Dexter is the protagonist of both the book and the show, but being a serial killer makes him a literary anti-hero. In both works, he follows an elaborate code of ethics and procedures taught to him in childhood by his father (which he refers to as "The Code") that hinges on two major points: Dexter can only kill other murderers and he should execute his crimes so as to never get caught. (IMDB)

My take: use my power for good and follow a code. I’m discovering just what my contribution to the world is, realizing, all the while, that relationships are the best reason I can imagine for being on earth, and in a body. While I’m unfamiliar with the intricacies of Jean’s story line, I get the Phoenix. Powerful and frightening, this bright shadow is unwieldy at best, and downright destructive, at worst. I am crucial to the unfolding of the universe—if anyone really knew me, they wouldn't understand or accept me. The mythical Phoenix carries a certain redemptive quality—rebirth, rather than mere remaking—hope for a better, stronger, faster version of me.

Jubilee, we come into the world alone -- and we leave the same way... the time we spend in-between... time spent alive, sharing, learning... together... is all that makes life worth living. (Jean Grey)

Sources Cited:

CBSS. (2008.) Marvel Comics vs. DC Comics. Retrieved on Oct. 17, 2010 from http://www.comic-book-and-strip-service.com/marvel-comics.html

IMDB. (2010). Dexter Morgan. Retrieved on Oct. 17, 2010 from http://en.wikipedia.org/wiki/Dexter_Morgan

Grey, J. (n.d.).The Uncanny X-men. Retrieved on Oct. 17, 2010 from http://marvel.wikia.com/Uncanny_X-Men_Vol_1_303

Wiki Answers. (2010). What is Jean Grey’s weakness? Retrieved on Oct. 17, 2010 from http://wiki.answers.com/Q/What_is_jean_grays_weakness_in_x-men_last_stand