Well, it's highly likely that there is. The Harry Potter fanfic community is vast and full of diverse ideas. Writers often explore unique combinations like this. In such a fanfic, perhaps Harry's Animagus form could have features similar to a basilisk, like the deadly stare or the ability to move through small spaces like a snake. He might also face challenges or advantages based on this form in the story, which could make for a very interesting read. You should start your search on popular fanfic sites and see if you can uncover this kind of gem.
A possible plotline could be that Harry's basilisk - related Animagus form is a result of some ancient magic that was dormant in him. The Ministry of Magic might see this as a threat and try to hunt him down. Meanwhile, Harry has to figure out how to use his new form to protect himself and his friends. He might meet other Animagi who have similar but different forms, and they could either help or hinder him. Along the way, he could also discover new spells or powers that are related to his Animagus form and use them to fight against the dark forces in the wizarding world.
In a 'harry is a basilisk animagus fanfiction', the plot could involve Harry being an accidental basilisk animagus. At first, he's scared of his new form. But as he learns to control it, he uses it to his advantage. For instance, he might use his basilisk form to scare off Death Eaters or to find out secrets in the Forbidden Forest. He would also have to deal with the prejudice that comes with being associated with a basilisk.
I'm not sure of a specific 'harry is a basilisk animagus fanfiction' off - hand. You could try searching on fanfiction - specific websites like Archive of Our Own or FanFiction.net. There are likely many creative takes on such an idea within the vast world of Harry Potter fanfiction.
Yes, there are many fanfictions that focus on other aspects such as adventures, friendships, and magical mysteries involving Harry Potter and the concept of a Basilisk Animagus without any sexual content. You can search on fanfiction - dedicated websites and look for tags like 'adventure', 'friendship' or'mystery' along with 'Harry Potter' and 'Basilisk Animagus' to find such works.
Perhaps a Basilisk Animagus could have a special connection with the other snakes in the wizarding world. In the story, they could communicate with snakes to gather information. This would give them an edge in situations like uncovering plots within Slytherin house, as the snake is the symbol of Slytherin. They might be able to understand the secrets that the snakes around the Slytherin common room are aware of.
A Basilisk Animagus could interact with Harry by initially being seen as a threat. Harry, having faced a Basilisk before, would be on high alert. But if the Basilisk Animagus was on the side of good, they could prove their worth by helping Harry fight against Voldemort. For instance, they could use their snake - like senses to detect Death Eaters approaching.
Another interesting plot could be that the Basilisk Animagus is an ancient magical being that has been awakened in modern times. Harry Potter and his friends have to figure out how to communicate with it and learn from it. The Basilisk Animagus could teach them new spells or ways of using magic that have been forgotten. They could go on a journey together to discover the origin of certain magical artifacts, all while building a relationship based on mutual respect and not involving any sexual elements.
One possible fanfic could be where Harry discovers he is an Animagus early on. His familiar could be a phoenix, for example. In this fanfic, the phoenix could guide Harry through difficult times, and their bond could be a source of strength against Voldemort. Harry could use his Animagus form, perhaps that of a stag like his father, to move around secretly and the phoenix familiar could provide additional protection and wisdom.
One great Animagus Harry fanfic is 'Harry's Hidden Form'. In this fic, Harry discovers he's an Animagus early on and it's a hawk. The story follows how he uses this new ability to his advantage in the wizarding world. It has some really cool action scenes where he scouts out Hogwarts as a hawk.