X-Men: Days of Future Past:
Radio host: We talked about Xavier's theme which almost acts as the central theme for the film because his story is so important, and it hovers around him. Since the film is about hope, and his character is about hope and rediscovering his hope, kind of a lost soul, where did you really draw the music from [...]?
John Ottman: [...] I knew what the character's challenge was, what the film was about, so I tried to create a piece of music or a theme that could play both sides, sort of despondent and tortured, but also be designed so that it can be hopeful as it evolves later in the movie. I started sketching on an electric piano, and it sounded so cool and vintage [...]. Early in the movie, when it's just very subtly underscoring him, it's a lot of electric piano within the strings.
John Ottman: Magneto's theme is a very simple "baauum baaaaw." That's basically it, it's so simple you can identify with it and feel it. [...] When he does his stuff at the end and you hear that big sound, it's bigger than it ever was before, and it ties things together.