Mystique

Not terribly much is publicly known about the mutant terrorist/mercenary known as Mystique, though she is, in one identity or another, on most countries' Most Wanted lists. She's currently a high-ranking member of Magneto's Brotherhood of Mutants, but she does take the occasional freelance job on occasion.

Background
Raven Darkholme is much, much older than she looks. Born sometime in the middle of the 19th century, she would be the first to tell anyone that her first fifty or so years were fairly uneventful. Well, there may have been one or two pitchfork-wielding mobs and one well-meaning but ultimately mislead attempt at an excorsism, but those are tales best left in the past, as far as she's concerned. It wasn't until around the turn of the century where she truly believes her life story to have begun. It was then, when she was working as a private detective, when she met Irene Adler, a woman who would come to be known as Destiny. Like her, Irene was a mutant (though the term had yet to be coined to describe such unique individuals as themselves). Where Raven was gifted with shapeshifting and an apparent immunity to the effects of time, Irene was a precognitive with uncannily accurate- if somewhat difficult to decipher- predictions for the future. Irene hired Raven to help decipher her diaries, and it was during these cases where the two fell in love. Same-sex couples were not particularly common during these times, so Raven took to taking a male form when in public with her lover, matching her seeming's age to Irene's as the decades passed. Raven did not spend all of her time with Irene, however. During the second World War, she spent much of her time traveling Europe working as a spy, though it was never entirely sure which side she was working for... other than herself, of course. She did assassinate several high-ranking German politicians and one or two Generals, though it's entirely possible this was purely for the money she received for it, rather than any interest in the destruction of the Nazi party. She wasn't exactly heartbroken when the Fuher's house of cards came tumbling down on him, though- in fact, she and Irene enjoyed a very fine bottle of French wine she'd smuggled back home to celebrate it. During the Cold War, she was on a mission posing as a German spy known as Leni Zauber when Victor Creed- or Sabertooth- pulled her out of a dangerous situation. The two had a very short-lived but intense affair, after which she was left pregnant with Victor's child. The baby, whom she named Graydon, was sent to boarding school as soon as he was old enough, and in the following years, she only kept tabs on him long enough to find out whether he would manifest any gifts similar to her own, or the boy's father. When he didn't, she decided he was not going to be useful to her, and abandoned him completely- in fact, she left him to die after he witnessed her changing her form. It's very likely this act that would later prove to be the catylist for Graydon's hatred of mutantkind. Sometime much later, she was living very comfortably as the wife of a German nobleman, the Baron Wagner. She became pregnant once again, but this time the baby was most certainly not a flat-line human. In fact, the child was born covered in blue fur, with yellow eyes, bizarre hands and feet, and a spaded tail. The shock of the birth forced her to revert to her natural form in front of the midwife, who soon alerted others, and she was forced to flee. In order to hasten her escape, she once again abandoned her child, letting the nearby river's current take the boy who would grow up to be Kurt Wagner. Sometime after this, she met Erik Lensherr, the mutant known as Magneto. His cause of mutant freedom and supremacy struck a chord with her, and she soon joined his cause, rising in the ranks of his Brotherhood of Mutants. She recruited many young mutants to their cause, including a Southern woman going by the name of Rogue, who she took a particular interest in, due to one of her now-deceased lover's journals indicating that she would be extremely important to the fate of mutantkind- or so that's what Raven /thought/ the entries meant. While she acted quite maternal towards Rogue, she was also very manipulative of the young woman. When Rogue got sick of the manipulation and Raven driving driving her towards the more militant actions of the Brotherhood, she left the organization, and Mystique. Raven is still with the Brotherhood, though Erik puts up with her taking the occasional sabbatical to do a freelance job every so often. Mercenary work pays very, very well for her, and she does put some of that money towards the cause.

Personality
The first word that comes to mind when discussing Raven Darkhome is "cold." While she is not entirely unfeeling, she is very... distanced from her emotions most of the time. She could be considered a functioning sociopath. She doesn't form emotional bonds so much as affections for individuals, particularly those who she thinks are useful to her. She is very much a user, who sees people for what they can do for her, or can be used to make other people do things for her. Irene has probably been the closest she's ever had to a real friend, and possibly the only person she could say she's ever loved (including her children). She is not particularly cruel or sadistic, however. She does not have violent impulses so much as simply a willingness to commit violence if she feels it is necessary. She takes no pleasure in the act of killing or hurting someone. She doesn't regret it, unless she's caught, but she doesn't go out of her way to break laws. She truly believes that mutantkind are superior to humanity, and believes that they will likely replace them as the dominant species on Earth in her lifetime (of course, given that she hasn't aged in over a hundred years, her lifetime is likely a very, very long time), and she's perfectly willing to do what she can to speed this process along.