There's no way Naruto can be the father of Lin Beifong in any legitimate sense. The two characters belong to entirely separate fictional settings. Naruto has his own story in the Hidden Leaf Village with his family ties related to Konoha. Lin Beifong, on the other hand, is an important part of the Avatar world's Republic City. Their abilities, cultures, and storylines are so distinct that it would be a very odd and non - canon pairing in fanfiction.
A strong and noble character like Mako could be a great love interest. He has his own sense of justice and duty, which could match Lin's. They could bond over their shared experiences in the police force and protecting the city. Their relationship could start as a mutual respect for each other's skills and then develop into something more romantic as they get to know each other on a deeper level.
One common theme is family. Since the Beifong family has a long history in the Naruto world, many fanfics explore family dynamics, like loyalty, heritage, and the passing down of skills. Another theme is power. How the Beifong characters develop and use their unique powers is often a big part of these fanfics. Also, friendship can be a theme, as they interact with other Naruto characters.
Since I don't have the actual text of the 'opal short story', it's hard to say for certain. It might be a story that revolves around the discovery of an opal. Maybe it's set in a mining town where people are searching for opals, and the story could involve the hopes, dreams, and rivalries among the miners. It could also be about an opal that has been passed down through generations in a family and the secrets it holds.
Well, 'black opal novel' could potentially revolve around a character who has a special connection to a black opal. Maybe it's a symbol of power or a family heirloom. It could also be set in a place where black opals are found, like Australia perhaps, and the story could involve the mining, trading, or theft of these precious stones. There could be complex relationships between the characters driven by their desires for the black opal.
The Opal Octopus is a remarkable being in the Fantasy Forest. It's not just its opal - like exterior that makes it stand out. It has a gentle nature, which is quite unusual for an octopus. It uses its tentacles not just for locomotion but also to interact with other forest dwellers. For example, it can use them to offer a helping hand (or tentacle) to a small animal in need. The patterns on its body seem to tell a story of the forest's history, as if it has absorbed the essence of the Fantasy Forest over time.
One possible theme could be her struggle with authority. If she's angry, it might be because she's facing issues with those in power over her in the story's universe.
A frequent theme in toph beifong crossover fanfiction is friendship. When she meets new characters, the development of new friendships (or rivalries) is a big part of the story. Also, self - discovery is common. Toph often has to re - evaluate who she is and what she can do in these new and unfamiliar settings. It's like she's starting a new chapter in her life and learning more about herself in the process.