Who would be the most interesting character to focus on in an Undertale One Punch Man fanfiction?

I think Monika would be really interesting. In DDLC, she has that self - awareness and a certain level of power over her world. If she were in Undertale, her attempts to understand the very different rules of that world would be fascinating. She might try to use her powers to change things, but in Undertale, the concept of determination and the power of the player is very different. So seeing her interact with characters like Flowey, who also has some unique powers and knowledge, could lead to some really intense and thought - provoking scenes.

Sans is another great choice. His laid - back but extremely powerful nature in Undertale would create a lot of interesting dynamics in a Deltarune world. He could befriend or baffle the Deltarune characters. For example, his time - related abilities would be very different from anything in Deltarune, and it would be fascinating to see how he uses them in a crossover situation, like against the Darkners.

Issei and Tatsumaki would also be a fascinating pair. Tatsumaki is a very powerful and prideful esper. Issei, with his own set of powers and a bit of a brash personality at times, could either clash with Tatsumaki or, in an unexpected turn, they could find common ground and work together against a common enemy.

Ruby and Saitama would be an interesting pairing. Ruby is young and full of energy, always looking to improve, while Saitama is already overpowered but has a simple - minded approach. Their interactions could be both humorous and inspiring. Another great pairing could be Weiss and Genos. Weiss is elegant and proper, and Genos is a cyborg with a serious demeanor. They could contrast and complement each other well.

Definitely Naruto and Saitama. Naruto's energetic and determined personality against Saitama's laid - back and seemingly bored attitude would create a great contrast. Naruto would be constantly amazed by Saitama's power, while Saitama would be a bit puzzled by Naruto's complex world of ninjutsu and chakra.

Harry Potter himself would be an interesting character to crossover into the One Punch Man universe. He would be completely out of his element in a world full of superheroes and monsters. His magic skills would be a new and strange power there. He could team up with Saitama and learn about a different kind of heroism. Also, his experiences with fighting Voldemort could give him unique insights when dealing with the villains in One Punch Man's world.

I think Eren and Saitama would also be a great pair. Eren has his complex motives and the power of the Titans, and Saitama is so simple - minded yet incredibly strong. They could interact in a really unique way, like Eren being all fired up to fight Titans and Saitama just being like 'Oh, that's nice' and then one - punching all the Titans. It would be a contrast of personalities and powers.

Another interesting pairing could be Tatsumaki from One Punch Man and Erza from Fairy Tail. Tatsumaki has powerful psychic abilities and a somewhat haughty personality. Erza, on the other hand, is a strong and disciplined mage. They could have a rivalry at first, both being very confident in their own powers. But as they face a common enemy together, they could learn to respect each other's abilities and form an unlikely alliance.

Definitely Mob and Saitama. Their personalities are so different. Mob is a shy and emotional high - school boy with powerful psychic abilities, while Saitama is a bored and seemingly emotionless hero who can defeat any enemy with one punch. Their interactions would be full of comical misunderstandings and also opportunities for character growth.

One idea could be that Saitama from One Punch Man ends up in the Undertale universe. He might accidentally punch some of the monsters there, thinking they are threats like the monsters in his own world. But then he realizes that in the Undertale world, things are more complex, and not all monsters are purely bad. Another idea is a crossover where Frisk from Undertale somehow gains Saitama's power and has to navigate their own world with this newfound strength, changing the way they interact with both monsters and other characters.