User blog comment:Stryzzar/Amy or Samey - comparison/@comment-22535514-20140819140426/@comment-24152851-20140819144912

Precisely why they should return. We found out so little about them, but only scratched the surface of the longest most complex conflict of the series. Their conflict predates TDI and judging from what Amy said started off when they were born. This is just throwing the first pebble into the water, now that Amy knows Sammy no longer lets herself gets pushed around, the conflict will have to step up a level. The b****y woma-child with a superiority complex will desperately try to regain the authority and power she's so used to having. Might pave way to a villain alliance, as she struggles to get her power back. Meanwhile now that Sammy has cut the bonds from her sister, she's free to go interact with anyone else, a whole cast out there waiting.

The conflict was what started them and made them interesting, but now they can step away from it and gain new plot just as any other character. Of course that doesnt mean the conflict will cease to exist, but it will no longer define them.