What's interesting is that the character will also be seen in Fox's X-Men: Days Of Future Past, but will be played by a different actor. Director Bryan Singer previously tweeted that he casted Evan Peters for that role in X-Men: Days Of Future Past.
It should be interesting to see how and if Fox and Marvel will resolve the situation of having two different Quicksilver in the film. Of course, if they decide to use the same actor and allow the character to be used in both film, it would help unify "Marvel Cinematic Universe".
Quicksilver, the mutant son of Magneto who super speed, has been quite a popular character in both The Avengers and the X-Men universe. His relationship with his father and sister, Scarlet Witch, has been the center of many storyline in the Marvel universe.