If you haven't, feast your eyes.
Rather conspicuous by his absence is Luke Skywalker, played by Mark Hamill. While we get a voice over from him in the second teaser, we have yet to actually see him in any of the teasers or trailers released for the film. When co-writer and director J.J. Abrams was asked about said absence, he had this to say:
"The fact that Luke is being kept away from the promotional materials is no accident"
This has lead to rampant speculation among the fan base that Luke has, in fact, turned to the Dark Side of the Force and become a Sith Lord, like his father Darth Vader/Anakin Skywalker before him.
But he can't. Or, at the very least, he shouldn't.
The problem with Luke succumbing to the Dark Side and becoming a "bad guy" is that it flies in the face of the trilogy of films that started with Star Wars (1977) and ended with Return of the Jedi (1983). The entirety of those original movies leads to the one moment in Jedi when Vader realizes his son's life is more important to him than his devotion to the Dark Side and redeems himself by ridding the galaxy of the Emperor's tyranny once and for all, saving his son's life in the process. The son that never turned to the Dark Side. The son that never gave up on his father. That last effort robs him of his own life, but finally, fully turns him away from the Dark Side at the same time, even telling Luke "You were right. Tell your sister, you were right"
Luke never gave up on the idea that his father could be brought back from the Dark Side. He felt the good in him and knew he could be redeemed. And you know what? He was right.
So now, after 30 years, Luke himself has turned to the Dark Side? That makes zero sense to me. Not from a fanboy perspective, though I'll admit to being one, but from a storytelling perspective. I want JJ and his team to come up with an original, standalone film while still continuing the story that we all know and love. I don't want him to try to rehash plot elements from the original trilogy by trapping Luke in some ridiculous cycle where the son becomes the father and must also be redeemed or some such nonsense. Luke is the plucky young hero who defied all the odds and brought his father back from the brink. If you turn him "evil" now, you undo all of that in one stroke.