User blog comment:Project Predacon/Volume 2: Post Credits Scene Analysis/@comment-25110963-20141031005600/@comment-10390252-20141101142346

"Deep undercover mission" is my second favorite plot device to explain her absence. My top pick is that she's spent the last 17 or so years being hunted by the Black Hats; she made herself such a nuisance to them that they wanted her dead, so she fled her family rather than put them at risk because of her enemies.