One idea could be that an angel and a devil are forced to work together to save the world from a greater evil. They start off hating each other but gradually learn to respect and even care for one another.
A plot could involve Angel protecting Willow from a group of vampire hunters who mistake her for a dark witch. Along the way, they develop a deeper understanding of each other and their respective roles in the fight against evil. They might also discover a long - lost prophecy that involves both of them and has to do with saving the world.
A plot could revolve around a group of heroes who use angel blades to fight against a new, powerful dark force. They have to discover the true potential of the angel blades and how to combine their powers to defeat the enemy. For example, they might find that when all the blades are united, they can open a portal to a dimension where the dark force originated, allowing them to face it on its home ground.
A great plot idea could be that the shotgun the angel has is actually a cursed weapon. The angel has to figure out how to break the curse without losing the weapon's power. Or perhaps the fanfic could center around the angel's relationship with other celestial beings. They might not approve of the angel's violent methods with the shotgun and try to stop the angel from using it. This could lead to a conflict within the celestial realm.
One idea could be that N and Touko team up to save a group of endangered Pokemon from an evil organization. They use their unique skills and the bond between them to outwit the bad guys.
One idea could be that Naruto discovers his half - angel half - devil heritage during a dangerous mission. Maybe he starts to have new powers like the ability to heal rapidly (angel side) and also to unleash dark energy (devil side) which he has to learn to control.
One idea could be a crossover with 'Cardcaptor Sakura'. Daisuke could meet Sakura and they could both discover that their magical artifacts have some strange connection. For example, the Dark and the Clow Cards might react to each other in unexpected ways.
One idea could be that an unknown entity with angelic powers emerges in the Naruto world during a time of great turmoil. This entity could initially be seen as a threat but later turns out to be a force for good, helping Naruto and his friends in unexpected ways. For example, it might use its 'angel of darkness' powers to purify the corrupted chakra in some of the villains, turning them into allies.
One idea could be a character with a devil bloodline being initially shunned in the Hidden Leaf Village but then proving their worth in a major battle. For example, they could use their unique devil - like abilities, such as enhanced speed and strength, to turn the tide against a powerful enemy.
One idea could be that N and Touya team up to discover a new, rare Pokemon species in a hidden, untouched region. They face various challenges along the way, like dealing with a powerful and territorial Pokemon that guards the area. This could lead to them bonding and learning more about each other's views on Pokemon and the world.
Perhaps in the fanfic, Alice Angel has lost her memory. Henry, who has some knowledge about the strange place they are in, tries to help her regain her memories. Along the way, they discover secrets about the place and their own pasts. Their relationship grows as they rely on each other for support, and Alice Angel starts to see Henry in a new light, different from how she might have perceived others before.