The idea of Harry Potter raising Rias in Highschool DxD fanfiction is fascinating. First, we have to consider the different power levels and cultures. Harry is used to the wizarding world where there are rules about magic use and secrecy. Rias is in a world of devils where power and status are very important. Harry would have to adapt to her world while also teaching her things. He could introduce her to things like the Marauder's Map which could be useful in her world for spying or getting around undetected. And his ability to think on his feet in dangerous situations could also be a valuable lesson for Rias.
Well, it's a really wild concept. In theory, it could be possible. Maybe Harry Potter, with his magic skills from his own world, could find himself in the Highschool DxD universe and for some reason decides to take Rias under his wing. He could teach her some unique magic tricks that are different from the devil magic in her world. But it would be really challenging to blend the two very different universes' magic systems and storylines in a believable way.
It's quite an interesting idea for a fanfiction. For it to work, the author would need to establish some sort of crossover mechanism. Harry could use his knowledge of the wizarding world to help Rias in her challenges in the Highschool DxD world. For example, he might help her deal with some political intrigue among the devils using his own experiences with the wizarding politics. However, it would also need to be careful not to make the story too convoluted and keep the essence of both series intact.
Chapter 256, ", you've guessed it, right?", is the clearest early answer because it turns Imperial Inquisition's situation into a concrete plot event. The setup is The Phoenix Battle Group and the Allied Air Force's battle reports..., but the pressure keeps building through Truly speaking, Gu Hang was the first person from the entire army to....
Chapter 217, ", The Retired Veteran, Homeward Bound Like an Arrow", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter turns that into something concrete by moving from Cohen Puliya finally decided to return to his hometown, taking his... to His parents were originally supposed to be relocated as well, but....
Chapter 196, ", Did I Get Exposed?", is the clearest early answer because the hidden truth stops feeling like mere subtext. The chapter gives readers a real answer by opening on On the outskirts of Weixing City, Phoenix Monastery. and ending on Matins stood behind the head priest, gazing for a long time..
Chapter 142, ", New Troop Type", is the clearest early answer because it turns Rubbish Town's situation into a concrete plot event. The setup is This part of the work, he had almost completely handed over to..., but the pressure keeps building through The commander of the 2nd Infantry Division had hardly had any direct....
Chapter 335, "Tax Season Again - Part 2", is the clearest early answer because it turns Tianma Star Sector's situation into a concrete plot event. The setup is Firstly, before this, Gu Hang had already applied for an expansion of..., but the pressure keeps building through This wasn't indeed something Gu Hang did just to offset taxes, the....
Chapter 322, ", All Resistance Crumbles From Here", is the clearest early answer because it turns All Resistance Crumbles's situation into a concrete plot event. The setup is This was the second time Dress had seen the Phoenix's Angels come..., but the pressure keeps building through But the shock she felt was no different from the first time..
Chapter 158, "Star Realm Tunnel", is the clearest early answer because Rage Owl Star finally turns buildup into a real advancement. The chapter gives readers a real answer by opening on In this vast universe, the most critical reliance for interstellar... and ending on After pondering a bit, taking a detour to the Rage Owl Star System,.... In story terms, the chapter closes with Wang Jiarong was aware that Yelisia's cruiser was docked in orbit around Rage Owl Star.
Chapter 223, ", The Message from Nest Capital World", is the clearest early answer because it turns Low Energy Storms's situation into a concrete plot event. The chapter gives readers a real answer by opening on Miss Wang Qi came and went in a hurry. and ending on Of course, if there is something of particularly great value—whether.... In story terms, the chapter closes with The Empire defines the annual total value of production of an Imperial person as 1 Tax Currency.
Chapter 234, ", Quell the Wind! Slay the God!", is the clearest early answer because the violence around Quell becomes final instead of hypothetical. The chapter gives readers a real answer by opening on Fifty thousand soldiers, along with all their accompanying... and ending on The heavy grenade rifle, acting as a parallel machine gun, was more....
Chapter 231, ", Here Is Hell's Abyss", is the clearest early answer because it turns Spiritual Energy's situation into a concrete plot event. It opens with Anat had fired the last bullet in his grenade gun. and closes on In the eyes of many Demon Hunters and Battle Nuns, the very real soul....