Well, perhaps a theme could be the connection between Naruto's feet and his chakra control. Since chakra is an important aspect in the Naruto universe, it could be explored how his feet play a role in his chakra - related movements. Also, the idea of Naruto's feet in relation to his environment. For instance, how his feet adapt to different terrains during his missions, whether it's muddy swamps or rocky mountains.
Since Naruto is about ninjas, friendship, and achieving one's dreams, and if combined with Galatea, perhaps a common theme could be an unlikely friendship. Maybe Naruto befriends Galatea in a new world or situation, and they learn from each other. Another theme could be adventure, as Naruto is no stranger to going on quests, and he could bring Galatea along on his adventures in the Naruto universe.
If we consider non - inappropriate versions, common themes could be Aquaman's relationship with his underwater kingdom. His leadership and how he balances his duties as a king and a hero might be explored. Also, his interactions with other characters like his friends or family members in Atlantis.
One common theme could be Sasuke's growth and development. It might explore how he overcomes his past traumas and becomes a stronger person. This could be related to his relationships with other characters as well.
One common theme is friendship. Fanfictions often explore the deep bonds between Naruto and his friends like Sasuke and Sakura. For instance, stories might focus on how they support each other during difficult missions.
One common theme could be redemption. Maybe Hans is given a chance to redeem himself and prove his love for Elsa, and the pregnancy becomes a symbol of a new start for them. Another theme might be family and acceptance, as they deal with the reactions of their friends and family in the fictional world.
One possible common theme could be adventure. If it's related to a story world where Annabeth exists, adventure might be intertwined with the unique element of tentacles. Maybe she has to face some challenges involving tentacle - like creatures.
One common element could be the use of Naruto's world - building. Since it's set in the Naruto universe, there would likely be references to ninja clans, jutsus, and the Hidden Villages. For example, the story might be set in Konoha and involve Naruto using his Rasengan in some way.
One possible theme could be the struggle between good and evil within the context of their relationship. Gabriel is often depicted as a more complex character, sometimes on the wrong side, and Marinette is the hero as Ladybug. Their interactions in fanfiction might revolve around this moral struggle. Also, themes of redemption could be present, where Gabriel might have a chance to turn his actions around because of his relationship with Marinette.
A common theme might be the bonds that Nanaki forms. Given his nature, fanfiction could explore the deep and meaningful connections he has with his friends in the FF7 universe. This could include his loyalty, his wisdom, and how he imparts that to those around him. It might also touch on his place in the group dynamic, whether it's being a source of stability or a catalyst for change among the characters.
If we consider non - inappropriate interpretations, common themes could be their unrequited love. Maybe Obito's long - held feelings for Rin that were never fully expressed while she was alive.