In a crossover with the Devil May Cry series, Dante would be a top choice. His flamboyant fighting style and demon - slaying abilities would make for some exciting scenes when combined with the Persona - using Phantom Thieves. He could show them how to take on more powerful foes and they could offer him a different perspective on the human psyche which is related to the concept of Personas.
From the Attack on Titan universe, Levi could be an interesting character to include. His combat skills and no - nonsense attitude would contrast with the more laid - back nature of some of the Phantom Thieves. He could teach them new fighting techniques and they could help him in his fight against the Titans by using their Persona powers.
From the Resident Evil franchise, characters like Leon S. Kennedy or Jill Valentine would be great. They have experience with fighting bio - organic threats, similar to the infected in Left for Dead. Their combat skills and knowledge of survival in a world overrun by monsters could blend well with the Left for Dead characters. They could exchange tactics and weapons, and together face new challenges that neither group has seen before.
You could include characters like Naruto from 'Naruto'. His ninja skills and determination would make for an interesting dynamic with the Persona 4 characters. Also, characters from 'One Piece' like Luffy. His carefree yet strong - willed nature would contrast well. And of course, characters from 'Sword Art Online' like Kirito. His sword - fighting skills and experience in virtual worlds could add a new dimension to the fanfic.
Definitely Yu Narukami. He's the main character in Persona 4 and his leadership and strong Persona abilities make him a great addition to crossovers. Yosuke Hanamura is also popular. His comical nature and loyalty can add some humor and heart to the story. Chie Satonaka is another one. Her martial arts skills and determination are great traits in crossovers.
Joker is definitely one of the most popular. His cool and mysterious demeanor makes him a great fit in various crossovers. Also, Morgana is often included as his sidekick. Another popular character is Makoto, with her strong - willed and intelligent personality.
The characters would likely be initially cautious. For example, Yu from Persona 4 might be a bit reserved when meeting Joker from Persona 5, but as they learn about each other's goals, they would start to trust. Yosuke might be excited to see the more high - tech Metaverse compared to the TV World, and he could bond with Ryuji over their shared love for adventure. Chie would probably challenge Ann to a fight at first, thinking she's just a pretty face, but then realize Ann's strength.
If we consider a crossover with the Lord of the Rings universe, Aragorn could be a good fit. He's a noble leader and a skilled warrior. His presence could force the Boys to reevaluate their ideas about power and leadership, and he could also be a strong ally against any corrupted power - hungry characters from the Boys' world.
The Terraria Guide could be a great character to include. He has a lot of knowledge about the Terraria world, so in a crossover, he could be the one trying to figure out the new world they're in. For example, if it's a crossover with Terraria and Hollow Knight, he could study the strange bugs and lore of the Hollow Knight world.
If it's a crossover with Teen Wolf, Stiles would be a great character to include. His quick thinking and sarcastic nature would contrast well with the more serious Shadowhunters. He could also provide some unique insights into solving problems, especially when it comes to the werewolf aspects of the Teen Wolf world that the Shadowhunters might not be as familiar with.
Well, if it's a crossover with Sonic the Hedgehog, the fast - paced nature of Sonic could contrast with the slower, more strategic Pikmin. Sonic could use his speed to quickly scout areas for the Pikmin, and the Pikmin could then help Sonic by carrying items he needs to progress.
You could include characters like Harry Potter. His knowledge of magic from the Hogwarts world would contrast and interact interestingly with Louise's magic from 'zero no tsukaima'. Another good character could be Naruto. His determination and unique ninja skills would add a different dynamic to the story when combined with Saito's swordsmanship.