Abel

Abel(アベル) is a french mixed martial artist set to make his first appearance in Street Fighter IV. He is described as amnesiac, a "man with no past" looking to defeat surviving members of Shadaloo. Later in the game, it is revealed that he is the same as Seth which explains the changes in eye color Abel experiences

Personality
Abel is a strange individual. He usually talks about the "battle field". He fights to try and recover his memory, so most of the cut scenes you see him asking someone a question. If not, usually someone asks him a question, threatening him as well. Of course, having no memory he gets agitated, and simply gets ready for the fight. He is a man of little words simply trying to find himself.

Street Fighter IV
Abel was found in an abandoned Shadaloo base and raised by a mysterious soldier. Abel claims that he died recently, and since then he has had no family and no memories. He started a journey of discovery to find who he really was and where he came from. He first went to the detective, Chun-Li. Upon hearing his connection to Shadaloo, she recommended that he participate in the S.I.N. Tournament to learn more about his past.

During the course of the tournament, he came across Gouken, whose kind eyes reminded him of the man who raised him, and Guile, who was able to use the moves the soldier had used. Both Abel and Guile had questions for the other, but their fight escalated, and neither got the answers they sought. Abel eventually arrived at S.I.N. headquarters near Guile and Chun-Li. As Guile raced to rescue Chun-Li, Seth (or one of the 26 copies of Seth) stopped Guile in his tracks. Abel tackled Seth, allowing Guile to reach her before she died. Abel was surprised to find that they looked so similar. Abel was called "imperfect" as Bison appeared from behind and destroyed "Seth". Bison allowed Abel to leave unharmed for some reason. Abel was last seen looking at the ruined S.I.N. base with Guile and an unconscious Chun-Li.

Theories

 * It is STRONGLY implied that the soldier who raised Abel is Charlie. He is only seen in shadow, and he seems to be wearing glasses similar to Charlie.  His hair is much shorter than it had been (but of course, hair can be cut).  The major clues are that this soldier is very familiar with Shadaloo and that he knows how to perform Guile's moves.  According to Guile, the only two men on earth who can use the Sonic Boom and Flash Kick are himself and Charlie.
 * It is likely that Abel is either a failed version of Seth, or Abel is the original human that Seth and the 26 clones were based on.

Video
Abel vs Ryu in Street Fighter IV