Redemption can be another theme. Maybe Stain starts to see the error of his ways through his interactions with Iida. It's a way to explore the possibility of change in a character who was initially so set in his radical beliefs.
The theme of friendship or an unlikely bond can also be present. Despite their differences, they might find common ground or develop a connection that defies what one would expect. This can lead to stories about them learning from each other and growing as individuals within the context of their relationship.
One common theme is the conflict between their different ideologies. Stain has his extreme views on heroes, while Iida has a more traditional heroic view. This contrast often creates an interesting dynamic in the stories.
One common theme is growth. Both Iida and Momo are characters with great potential for growth in the original series. In fanfiction, they often grow together, whether it's in terms of their quirk development or personal relationships.
One common theme is mutual growth. They both inspire each other to become better heroes. For example, Deku's determination might push Iida to be more fearless, and Iida's sense of order and discipline can influence Deku to be more organized in his hero training. Another theme is friendship - turned - romance. Usually, they start as friends and classmates, and then as they get to know each other better, romantic feelings develop.
Another theme is the support they give each other in their respective goals. Hatsume with her inventions and Iida with his hero training. In many fanfictions, they help each other grow, for example, Hatsume might come up with a gadget that helps Iida in his combat training, and Iida might give Hatsume some advice on how to present her inventions better.
One common theme is friendship development. Since they are classmates in the My Hero Academia universe, many fanfictions explore how their initial acquaintance turns into a deep friendship. For example, they might start off just as study partners and gradually become more like siblings who support each other no matter what.
Well, it could be that Stain kidnaps Iida to use him as a bargaining chip against other heroes. He might think that by having Iida in his custody, he can make demands on the hero community, like asking for changes in how heroes operate or for certain heroes to be punished. Another possibility is that Stain wants to prove a point to Iida about the flaws in the hero system. He may hold Iida captive and show him examples of what he believes are the wrongdoings of heroes, trying to sway Iida's loyalty from the hero side to his own view of justice.
One place to find Stain x Iida fanfiction could be Archive of Our Own (AO3). There are often many creative and well - written stories there. Just search for 'Stain x Iida' in the search bar and you'll get a list of relevant fanfictions.
One common theme is friendship. Writers often explore how their different personalities interact and form a strong bond of friendship. For example, Iida's more serious and rule - abiding nature contrasting with Uraraka's more easy - going and friendly attitude.
The story could progress with Iida trying to escape on his own. He might use his intelligence and his quirk in unexpected ways to break free from Stain's clutches.
One common theme is the clash of ideals. Stain has his extreme views on heroes, while Deku is the epitome of the traditional hero concept. Another theme is redemption. Sometimes Stain is shown on a path of redemption through his interactions with Deku.
One common theme is the exploration of Stain's sense of justice. Since he has a very distinct view on what makes a true hero, fanfictions often delve into this concept, comparing it with the more mainstream ideas of heroism in the 'boku no hero academia' universe.