Sequel to Dante in Highschool DxD, this will center around Vergil and his desire for more power in Bleach. I really enjoyed writing my idea for Dante, so I'm excited to write this. Nobody has used my ideas yet, although, if I remember correctly, someone did want to use one in the future.
Obviously since Yamato is with Dante, Vergil won't have it, but there's no big issue with that, as he could receive a Zanpakuto somewhere in the plot. I don't exactly know what said Zanpakuto's abilities would be, suffice to say Vergil would probably unlock both Shikai and Bankai, eventually. He'd still have the ability to use the Summoned Swords, I'd liken their power equal to a Quincy Arrow. And just like Dante, he'll still have the use of both Devil Trigger and Sin Devil Trigger.
Since Vergil only uses Dark Slayer Style his power set is limited, though he can mimic some of Dante's various moves. I think that Dark Slayer is solely meant for use with the Yamato, so I don't know if he'll be able to use it correctly with a different sword. You could give him Beowulf to compensate, though I don't know how useful it will be in Bleach's world.
Since this is basically a spin-off of Dante in Highschool DxD, the beginning will be the same. After Dante is sucked into the portal, Vergil quickly realizes the missing Yamato and jumps in to retrieve it. Unfortunately, because he was a bit slow the portal's destination changed, leading to Karakura Town instead of Kuoh. He arrives there, weaponless, with the same age regression as Dante. Intrigued by the possibilities, Vergil decides to live in this town for a period of time, while researching ways to return home. Surprisingly, he doesn't sense any demonic energy, though there is something that grabs his attention. (I don't know whether Dante and Vergil have sensory abilities or not, so I'm just giving some to Vergil) Two signatures fighting, one is animalistic and corrupted the other is more balanced, but not human either. Heading to the location, he finds nothing except two vague outlines of creatures. Slowly, the outlines become more defined and then become solid. It's a strange beast with a hole in its chest and a woman wearing a uniform of some kind. It's Rukia, fighting a very low level Hollow.
Amused, Vergil decides to slay the beast, to gauge how strong he is in this new world. Rukia, aware of him but unshaken, is stunned when several spectral swords pierce the Hollow, killing it. And that's where I'll leave it off.