Interestingly, his X-Men co-star James McAvoy played Macbeth in the West End last year — and gave Fassbender some literature and advice on playing the Thane.
Daily Mail (x)
But the truly hard part was trying to find the relationship beat required because Charles and Erik haven’t seen each other in so many years and their feelings towards each other have been pent up for so long. So it was an important scene, given how emotionally invested Erik is in his friend and continues to be throughout the other films. To have that emotional resonance, it was an important one to get right.