Fanfiction often takes liberties with the relationship between Izuku and Toga. It could also involve them teaming up against a common enemy. This would require them to put aside their differences and work together. Writers can use this to create exciting action - packed scenes and explore how they would communicate and cooperate in such a situation.
Toga is still alive in the manga. The creators haven't decided to end her character's journey with death. Usually, such major plot points are well-signaled and haven't happened for Toga so far.
Maybe Toga uses his powerful abilities. He could have some special powers like super strength or the ability to manipulate time or space. With these, he might be able to stop Kikyo from harming Kagome.
In fanfiction, their relationship could develop through a common enemy. Suppose a new, powerful villain emerges who threatens both Toga's goals as a villain (in her own twisted way) and Izuku's mission to protect. They might be forced to team up against this foe. During their time together, they would learn about each other's strengths and weaknesses, and this could lead to a deeper understanding and a change in their relationship.
Their relationship could start with mutual self - interest. They both recognize the power and chaos the other can bring. For example, Toga's ability to transform could help Villain Deku infiltrate places, and he can offer her protection in return.
To some extent, it is popular. There are many online platforms where MHA adult fanfiction can be found. The popularity might stem from the fact that the MHA world has a rich cast of characters and a complex universe. Fans who enjoy adult - oriented storytelling might use these characters to create their own narratives that are more in line with their interests in terms of relationships, power dynamics, and personal growth, all with an adult twist.
Several characters have met their demise in the MHA manga, but it's a bit complex to list them all precisely. Some of the notable ones include [mention specific characters if known].