There are some Ben 10 harem fanfictions that explore alternate universes. In these stories, the harem members might have different powers or backstories compared to the original series. This can create really interesting and unexpected plot twists.
One popular Ben 10 harem fanfiction might be those that focus on unique character interactions. For example, stories where Ben has to deal with the different personalities in his harem while on an adventure. It could involve his alien forms playing different roles in these relationships.
One popular Ben 10 Ben Harem fanfiction could be those that focus on Ben's adventures with his harem while facing new alien threats. For example, a story might have Ben and his harem working together to stop an evil alien warlord from taking over the Earth. They use their combined powers and skills to outwit the enemy.
In many 'Ben 10 Harem Fanfiction' stories, a prevalent plotline is the exploration of different alien cultures within the context of the harem. Since Ben has the Omnitrix and can transform into various aliens, his harem members, who might be from different species or have different backgrounds, introduce him and the readers to unique cultural elements. This can range from their social hierarchies, mating rituals if appropriate and not overly sexualized, to their ways of communication. Another plotline could be about how the harem members adapt to living on Earth, or how they help Ben in his fight against villains that target Earth specifically because of his presence or the presence of the Omnitrix.
I'm not sure about extremely popular 'ben 10 harem fanfic' stories specifically. However, in the world of fanfiction, there are likely some that have gained a following among 'Ben 10' fans who are interested in the harem genre. You can probably find some by searching on popular fanfiction websites.
One popular 'Ben 10 Ben and Gwen fanfiction' could be those that focus on their adventures in different dimensions. For example, there might be a story where they end up in a dimension full of magical creatures and have to use their combined skills to get back home. Another could be about a time when Ben loses his Omnitrix and Gwen has to use her magic to protect them both until he gets it back.
One popular OC is a female alien with telekinetic powers. She stands out because her powers are both useful in combat and in helping Ben solve problems. Another is a human girl who is a tech - genius. She can upgrade Ben's alien devices and often comes up with clever plans. There's also an OC that is a shape - shifter from a previously unknown planet, which adds an element of mystery to the harem.
There are fanfictions where Mal and Ben face a new villain together. This could involve them using their combined skills, Mal's magic and Ben's leadership. Some fanfictions also explore their life in Auradon from the perspective of other characters in the story, which gives a different take on their relationship.
One popular 'Ben 10 Female Fanfiction' story could be those that focus on female characters taking on new and unique roles within the Ben 10 universe. For example, a story where a female character becomes a powerful alien hybrid in her own right, similar to Ben but with her own set of challenges and adventures.
Some popular ones often involve anime or book series. For example, in the 'Naruto' fanfiction realm, there are harem stories where the main character, Naruto, is paired with multiple female characters from the series. These stories usually play on the idea of the main character's charm and how different relationships could develop.
Another idea is to have Ben 10 cross over with a futuristic sci - fi setting. His harem could be made up of female alien species he encounters. They could be intrigued by his ability to transform and his heroics, leading to a harem - like situation where they all vie for his attention.
One idea could be Ben Tennyson getting transported to the DC universe and his Omnitrix's powers attracting the attention of various female characters. For example, Wonder Woman might be intrigued by his unique abilities and his sense of justice. Another could be that he teams up with some of the female superheroes to fight a common enemy, and during the process, a harem - like relationship starts to form.