Obviously, Birdy herself is a very popular character to focus on. Her dual nature as an alien and her life on Earth make for a lot of interesting storylines. Tsutomu is also a key character. His relationship with Birdy, from being initially shocked to gradually becoming her partner, is full of potential for fanfiction.
I think Nataru is a character that can be really interesting in fanfiction. He has his own unique abilities and a bit of a mysterious past. Fanfiction could explore his relationship with Birdy and Tsutomu in more depth. Maybe he has some secrets that could change the whole dynamic between them. Also, the scientists on Earth who are aware of Birdy's existence could be a focus. How do they try to study her? How do they keep her a secret from the rest of the world? There's a lot of potential there.
Marshall is often a popular choice. His clumsy yet endearing nature can be played up in fanfiction, especially when he's using his Mighty Pups powers. He could be in a situation where his firefighting skills are put to the ultimate test and his friends have to rely on him.
Some excellent characters for Birdy the Mighty Crossover fanfiction are Lelouch from Code Geass. His strategic mind and his complex personality would add depth to the story when combined with Birdy. Also, Asuna from Sword Art Online. Her combat skills in a virtual world and her strong will could lead to great team - up moments with Birdy. And don't forget about Ichigo from Bleach. His ability to see spirits and his powerful sword - fighting skills could make for some exciting crossovers with Birdy in different scenarios.
Captain America is also a favorite. His old - fashioned values in a modern world of superheroes can create great conflict and story opportunities. He can be a moral compass for the team in fanfiction.
One of the most popular characters to focus on is likely the main protagonist. His leadership skills and complex personality make for great storytelling. Another could be the tech - savvy character. Their ability to get the team out of tough situations using technology is always exciting to write about.
Andy Herrera is often a popular choice. Her strong leadership skills and complex family background make for great fanfiction material. Writers can explore her relationship with her father, Pruitt, and how she balances her personal and professional life.
Hannibal is often a popular focus. His leadership skills and strategic mind make for great storylines. Writers can explore his past military experiences in more detail or create scenarios where he has to outwit an even smarter adversary.
Well, clearly Himari is a very popular character to focus on. Her powers, her loyalty to Yuuto, and her feline - like charm make her a great centerpiece for fanfiction. Yuuto is also frequently the focus, as his journey of self - discovery in the world of the supernatural is ripe for exploration. Then there's Kuesu. Her stoic nature and her role in the group can be an interesting aspect to explore in fanfiction, especially in relation to how she interacts with Himari and Yuuto.
Kazuya is also a common focus. His insecurities and growth throughout the story can be interesting to expand on in fanfiction. Writers can delve deeper into how he overcomes his self - doubt in relationships.
Spectra is often a popular choice. His complex character, being an antagonist with his own motives and backstory, offers a lot of room for exploration in fanfiction. Writers can delve into his past, what made him turn against the Battle Force 5, and maybe even explore a redemption arc for him.
Definitely Tony Stark. His complex personality, his wealth, and his role as a sort of father figure in some scenarios make him a great focus. He can be shown as mentoring the younger Avengers or having heart - to - heart talks with them about responsibility.