Originally Posted by Mrs Vimes
I don't really see Erik helping Charles build the Cerebro. To allude to a reconciliation between the years would IMO kinda detract from the whole tragic ending of FC. And to have them be at odds at the start of the film, then reconcile and work together for a bit, then fall apart again sounds a tad too busy.
And while Magneto helping out with Cerebro is important for the X2 storyline, in X1 its importance is explaining how Magneto can avoid being found by Charles using the Cerebro. Which doesn't really make sense anymore post-FC. Magneto blocks out Cerebro because he took the helmet from Shaw, not because he had special insider knowledge of Cerebro.
Who says they have to reconcile to build cerebro again? If it's a mutant against human conflict again they may be forced to work together ala X2.