Dawn and Rini
I am suddenly struck by how much Dawn of Buffy the Vampire Slayer has in common with Rini of Sailor Moon. Swap sister for mother, a likely crush on Spike for a barely subtexted Electra complex, Scouts for Scoobies, and the crystal for the key/gate. Each tumbles late into her series full-formed... Dawn never got a "Dark Lady" storyline, but boy! would she not have taken that offer just like Rini did? and would it not have fit? I'm drawn to using Wolfram & Hart for the Doom Phantom in this scenario, but any of a zillion other powerful black hats could serve. Another for the list of overlapping archetypes there.
Of course, the big difference -- besides Rini not being a construct (she's just from the future) -- is that "Mini Moon" eventually gets super powers, too. "Little Bit" does not, unless the comics have changed that.
Of course, the big difference -- besides Rini not being a construct (she's just from the future) -- is that "Mini Moon" eventually gets super powers, too. "Little Bit" does not, unless the comics have changed that.