Good idea, technically, she can look lik ewhat she wants, she could be really old for all we know!
It would be good to show the relationship somewhat, as long as they keep it as a friend etc, it would interesting to see her reaction to Magneto having a child with a normal human.
Drama first please, action is not even important at all.
I would say that action is important. With a mutant like Magneto, a comicbook-derived movie, and the necessity of conflict occurring within the drama, then action is required as a result of those conflicts.
Magneto will obviously do something like take revenge on the Nazis who killed his family, which will result in an action sequence.
In his actual comicbook origin story, there are action scenes and power displays. And so there should be in the movie. There is a Magneto prequel story to X1 (in a graphic novel that also contains prequel stories on Rogue and Wolverine) in which Magneto takes revenge on a Nazi war criminal. And it does include action within the dark dramatic content.
I would like Mystique to be the one who helps Magneto tracks down the particular 'Dr Death' involved in his family's extermination. Mystique was a spy in the war, taking the identity Leni Zauber (a deceased German agent).
She has a particular skill for espionage and infiltration, aided of course by her metamorphic powers.
She later married, had an affair and gave birth to Nightcrawler but abandoned him and he was raised by a gypsy called Margali Szardos. All of which could be included in the movie, especially if a voiceover by Ian McKellen can explain events not necessarily shown in full on screen.
Magneto's own children could also make an appearance. I can imagine a voiceover in which Magneto laments that either he wished he had children (unaware that he had) or that he was aware but never knew what happened to his children... then we see a shot of Scarlet Witch and Quicksilver somewhere in Europe playfully showing off their powers in some sibling mischief. It could be a touching scene with them wondering who their father was, what kind of man he was, hoping he was a kind and benevolent man....
