- Archangel Gabriel: Mostly For the Funnyz. The mental image of a Serafall being jealous/annoyed/incredulous at her rival "goody twelve-wings Gabriel" becoming a love rival is funny enough to picture on its own, but if you add the rest of The Great Seraphim (Uriel, Raphael, and super Nice Guy Michael) acting as Overprotective Big Brothers to their ingenue and something of The Ditz sister and threatening Harry to go (literally) full Old Testament on his ass if he ever does anything to hurt her or make her a Fallen Angel, plus Azazel and Lash plotting to bring about that exact outcome, and the rest of the world having the Entertainingly Wrong idea that Harry was helping the Angels with their Can't Have Sex, Ever problems simply because he wanted to tap that from the very beginning, it becomes a SNAFU worthy of Harry Cosmic Plaything Dresden — Andrzej
- The Christmas Episode showed that Lash can remote-control illusions of her preferred appearance like one would with a videogame Player Character.
- Right after the Kyoto School Trip Story Arc, DxD!Lasciel demonstrated a complex magical technique that can create a soulless homunculus from a person's DNA sample in a matter of minutes.
- The Alice White Rescue Arc confirmed that Lash possesses her own soul distinct from Harry's.
- Finally, Harry can imbue objects with his own soul, as seen when he tried to use Soulfire to scan Sona, Reya and Tsubasa's Evil Pieces (and accidentally getting them to undergo Mutation as a side-effect).
Putting all this together, it could be possible for Harry to put a piece of Lash's soul into a custom-made homunculus based on DxD!Lasciel's own DNA, which could allow her to remote-control it as a corporeal avatar, or perhaps even grant "her" with some level of self-awareness in a Robot Me kinda way, or split the difference at a two-member Hive Mind — one Lash in Harry's head as always and another as an Artificial Human, both helping and annoying him in equal measure.
They could even go the whole way and put the entirety of Lash's soul in a long-lived homunculus, but that sounds like a bad call given how Harry's survivability would nosedive without Lash riding shotgun in his mind. And that's before considering how bad an idea would be leaving him alone with the Winter Mantle.
Now, why would a Puny Earthling be "supporting" heavy hitters such as "six Mother Goddesses, and thirty-seven each of the strongest Angels, Devils, and Valkyries" in an operation with at least an Class X Apocalypse How as the price of failure? It would make sense if said human was a Starborn, who through "a complex confluence of events, of energies, of circumstances [was born with] the potential to wield power over Outsiders."
From the The Dresden Files novels we know of one, maybe two, characters that fill the bill. And one of them we know for sure would risk a Fate Worse than Death to keep the world safe, perhaps even to the point he jumped into the seal so the Walker couldn't use him to drag itself out of the trap.
It would explain why there isn't a DxD!Harry in Bizarro World — "Ur-Harry" didn't technically die, or at least he didn't within his home Creation, meaning that his Soul didn't rejoin the Circle of Reincarnation and DxD!Harry was never born in modern times.
The Dresden Files' version of Earth instead after Houdini's actual passing. This "dual-citizenship" deal of his soul is perhaps what being a Starborn actually means and the real reason why his magic is effective on Outsiders.
As for why Harry was born before Houdini died, well, they lived in different Creations/Universes that work under very different fundamental rules. Who is to say that jumping from one to the other doesn't have Timey-Wimey Ball side-effects attached.
Maybe the whole reason why Harry de-aged to his teens upon entering Bizarro World is because the local universe partially recognized him as Houdini and "corrected" his age by taking away his last 30 years or so, which is the amount of time Ehrich Weiss has been dead according to the rumors. It wouldn't be that surprising considering such an unique set of circumstances and the fact that Bizarro World's reality is canonically stated to be glitchy since God's death.
Both Azazel and Serafall saw something about this when Harry Soulgazed them and unconsciously made the connection between him and Houdini, which is why they wrote Harry's In-Universe fictional counterparts as a descendant of the last true wizard.
Finally, if this is true, it would mean that Harry didn't ended up in Bizarro World by pure chance. His soul simply came back home at long last.
Jossed and ConfirmedStory Arc that Azazel wants to make a fictionalization of the Hero Faction to be the Arch-Enemy to the Wandering Wizard. This would work particular well in Miracle Levi-tan because the Foe Yay between Harry and Jeanne is the perfect set up for a tried-and-true Magical Girl cliché: the Love Triangle between the heroine, her love interest and the Dark Magical Girl.
- For extra awkwardness, Jeanne's little sister is a fan of the show. This means that the above development would give her the wrong idea about Harry and Jeanne. Whether Alice gets behind the pairing or merely has This Explains So Much moment, Hilarity would Ensue.
- Jossed. The Foe Yay-stic Dark Magical Girl role in the Show Within a Show went to Georg, or rather "Georgia", who's the Wandering Wizard's Old Flame (or so she tells herself), former magic apprentice, and currently a Stalker Without a Crush.