'Spider-Man: Brand New Day': Who Is Sara?

Warning: This article contains spoilers for "Spider-Man: Brand New Day." For months, audiences speculated over who Sadie Sink was playing in "Spider-Man: Brand New Day," a secret Sink avoided revealing at all costs. Spoiler alert: She's playing Jean Grey. While that casting will hardly come as a surprise to the hyper-online Marvel fans (and is hardly treated as a reveal in the movie itself), those audiences might be a bit more surprised to learn about Jean's sister, Sara. So who is Sara Grey, and what do the comics tell us about this character? Read on to find out. Who is Sara Grey . . .