Disclaimer: I do not own Final Fantasy 7, or any of the places or characters in it.
At this time, this is simply a one-shot, setting up an AU, the premise which is explained in the text itself. There is a possibility I'll come back to this after the...three...stories currently on the stove, but don't hold your breath.
It had taken her collapse to finally convince her to leave with him. While they packed, the debated heavily on where to run to - Midgar itself was immediately dismissed as too risky, and Wutai soon followed, since neither of them would have any hope of passing for native. Gongaga, Vincent eventually decided. It was small, out of the way, and held no interest for Shinra now that the reactor there had been completed.
While Vincent cast the strongest Sleep spell he could over the mansion's current inhabitants to prevent immediate pursuit, Lucrecia copied all of the files onto disks that had any information about Jenova or the project, as well as her personal projects, then destroyed the originals. She wouldn't make it easy for them to start this line of research up again. Plus, since she was still a scientist at heart, she would need the information as background for any effects of the handful of treatments she had already received. That done, the pair vanished into the night.
Their supplies ran out halfway to Cosmo Canyon, and for a brief time Lucrecia thought they wouldn't make it. Vincent hardly batted an eye, though; his marksmanship was enough to bring down some game, and they were able to forage to supplement the meat.
Nothing was so welcome to the travelers as the sight of Cosmo Canyon's bonfire blazing into the night. The chance to rest, and eat their fill, was too tempting to resist, and they stayed for several days recovering their strength. Finally, though, fear of pursuit pushed them onwards to the mountains and the jungle beyond them.