We wanted her to have powers that were interesting to look at on the page and that were sort of unexpected for a female character. It’s most often male characters that get the dramatic growing, shrinking, stretching powers, because those aren’t pretty powers.
The more we thought about this character, the more we thought that making her a polymorph might nicely parallel, in a metaphorical sense, a lot of her struggles in her non-super hero life. Shape-shifters in comics are most often cast as villains; characters like Mystique and Morph. We’re naturally suspicious of people with fluid identities. We assume they must be hiding something.
G. Willow Wilson, à propos de Ms. Marvel