Darwin, Another Non-First Class Mutant, Joins X-Men: First Class

It feels like it's been a while since we've had any X-Men: First Class news. There's been so many casting confirmations and rumors that it's getting hard to figure what X-Men are actually in this movie. Deadline New York announced that there is another mutant joining the cast. Edi Gathegi, probably best known for Twilight and Twilight Saga: New Moon, has joined the cast as Darwin. 

Darwin, as you may know, is pretty much the ultimate mutant. His power allows him to evolve and survive any experience. The concept is pretty cool. I just can't say I'm crazy about him being in this movie. What is going on in this movie? Why are we seeing all these non-First Class X-Men?  
 
So far we know that Emma Frost, Beast, Banshee, Havok and Mystique will be appearing along with Professor X and Magneto. Kevin Bacon is set as a villain, which hasn't been revealed so far. I think the best thing to do is not have high expectations for this movie. It's clearly not going to be a true close adaption to the comics. All we can do is hope that it will be entertaining and not too far off from what the characters should be.