The X-Men: First Class casting news seems to never stop! According to THR Rose Byrne from the TV series Damages is currently in discussions to co-star in Matthew Vaughn's First Class. She will take on the role of the character Moira MacTaggert, a scientist and an authority on genetic mutation. She'll be the love interest of Charles Xavier played by James McAvoy.
Byrne will join actors Michael Fassbender, Kevin Bacon, Jennifer Lawrence, Nicholas Hoult and Alice Eve who have already been cast in the film.
Here's a bit more information on the character from Marvel:
The daughter of a powerful Scottish nobleman, Moira Kinross' marriage to Royal Marine Commando Joseph MacTaggert proved disastrous. Whilst studying at college, Moira met and fell in love with Charles Xavier. They became engaged, pending the annulment of Moira’s marriage, but soon after Xavier was drafted into military service. Moira promised to wait until he was released, however while he was recovering from battlefield injuries she broke off their engagement without explanation. Later, whilst in New York City, Joe MacTaggert beat and sexually assaulted Moira, causing her to be hospitalized for a week and leaving her pregnant. From then on, Moira lived apart from her husband, although he refused to grant her a divorce, and she kept the fact that he had a son secret from him for twenty years.
Moira forged a brilliant career as a leading geneticist, earning a Nobel Prize, and founded a Mutant Research Center on Muir Island off the coast of Scotland. After renewing contact with Xavier, they discussed the possibility of establishing a school for training mutants. Moira became Xavier’s silent partner in founding the Xavier Institute for Gifted Youngsters and its’ first team of mutant students, the X-Men.
X-MEN: FIRST CLASS, follows the classic Marvel mythology, charts the epic beginning of the X-Men saga. Before Charles Xavier and Erik Lensherr took the names Professor X and Magneto, they were two young men discovering their powers for the first time. Before they were archenemies, they were closest of friends, working together, with other Mutants (some familiar, some new), to stop the greatest threat the world has ever known. But then “a rift between them opened, which began the eternal war between Magneto’s Brotherhood and Professor X’s X-Men.”