Fear my inspiration!
The year is 21XX. Copy-X has taken over Neo Arcadia and now rules it with an iron fist, persecuting reploids and hunting the last vestiges of resistance into extinction. Out in the wastelands, Ciel's resistance movement is on its last legs, and desperately needs a miracle just to survive, much less make any headway against X's rule. However Ciel thinks she may have found that miracle. On the edge of enemy territory lies a forgotten and dilapidated laboratory, rumored to the be final resting place of the legendary Maverick Hunter Zero. Betting on long odds, she leads a strike team into hostile territory in the hopes of awakening Zero and requesting his aid.
The insertion is successful and Ciel penetrates the interior of the lab, but the team accidentally alerts Arcadian forces to their presence and her escorts give their lives to buy her some time. However what Ciel finds in the inner-most lab is not at all what she expected. Instead of a deactivated reploid in a stasis tube, all she finds is a strange hunk of metal, mechanical in appearance but also strangely organic in a manner of speaking.
She's rather surprised when said hunk of metal starts speaking to her.
Zero's fate at the end of the Elf Wars was slightly different than it was in canon. Rather than rebuilding his body after the battle with Omega, Zero chose to go into stasis without repairing his battle damage, firmly believing that he'd never wake up again. When the lab's power went out during the 100-year timeskip, the stasis tube failed and Zero "died" without ever waking up, however his cyber elf didn't pass on for some reason (Cyber Elf X's influence?) and warped his body into a naturally-occurring biometal, similar to Model W. And as Ciel finds out very shortly after Zero's reawakening, she just so happens to be a perfect biomatch for "Model Z".
Unfortunately this leaves Ciel in a rather awkward position. Her gambit has paid off and Zero is awake again with his memories intact, but as the only one who can Megamerge with Model Z, the burden of saving the resistance now falls solely on Ciel's shoulders. This is a very big problem because Ciel is a devout pacifist, and has never even held a beam saber in her entire life. The question of experience can be remedied somewhat by Zero's support systems, but Ciel herself is not cut out to be a warrior... at least, not the way she is now.
And even then there are further complications. The system Zero uses to assist her in combat links Ciel's mind to Zero's cyber elf to the extent that she's started seeing his memories in her dreams, and nightmares of Omega and the Elf Wars are not the sort of thing she needs right now. And just when Ciel thinks Neo Arcadia is the worst of her problems, old ghosts from Zero's past return to haunt him once again, dragging Ciel further still into ancient conflicts that may be far more personal than she realizes...


