It seemed like a good idea to Vapula at the time, honestly. Being the Prince of Technology means you have to reverse engineer all of Jean's little breakthroughs, which isn't easy when you don't have access to God's blueprints like the Elohite does. But through experimentation, Vapula's pretty sure he can figure out how the Symphony works. Oasis was one such experimentation. Vapula was trying to create his own Infernal version of the Malakite, by combining Djinn and Calabite Forces with the Ramnant Forces of a few Malakim his agents tried to capture in the field (That's the problem with those darn blackwings: they're so uncooperative...), and the final ingrediant, a captured Reliever who was tortured and abused until it's Ethereal Forces were nearly gone.
The Balseraph assigned to the project, Stevrion, rebuild the little Reliever from the Forces up, using a Djinn's possessive nature to make the creature devotedly obediant to a master, a Calabite's destructive nature to make it into a lethal killer, and a Malakite to make it nearly unstoppable. The end result was Oasis, and she proved to be more then the sum of her parts. Oasis was a swift and agile little number, as well as a swift and lethal killer. Her mind was also a blank slate, allowing Stevrion to write whatever he wanted into her mind. He thus re-wrote her entire past, making her believe she was an ordinary human child who had been raised by him to become a skilled, but brainwashed ultra-competent assassin, and not a 10-Force based Abberation of Nature with the abilties of a Djinn, Calabite and Malakite.
Taking her out to Earth for the final field tests, Stevrion (in his role as Dr Steve) was sure his 30+ years of work would award him a promotion. And then Torg, Kiki and Bun Bun came. Things went South (or North, for a Demon) from there. Bun Bun and Kiki sabotaged the device Steve was using to control Oasis, just after he'd ordered her to fall in love with Torg. And the moment he tried to kill Torg himself, she went postal on him. Whether or not he was soul-killed or just sent into Trauma is still in question. As for Oasis, she apparantly was destroyed, but rather then be sent back to Hell (Stevrion had ommited giving her a Heart), she was tossed into Limbo, where she slowly healed her Vessel, and focused her thoughts on Torg, whom she still loved. Obsessivly...
Thus far, Oasis has returned from Limbo not once, but twice. And she seems likely to continue to return, as her Malakim parts seem to make both her immune to Trauma and impossible to capture. But she's still focused entirely on Torg, so her return to Hell is unlikely. Oh well... Vapula still has his notes, and he's pretty sure that the next model will have it's bugs worked out.