The Highschool DxD manga has indeed finished. It wrapped up after completing all the planned story arcs and providing a satisfying conclusion for the readers.
A great fanfiction could be a 'what - if' scenario. What if a certain event in Volume 10 had a different outcome? Maybe a character who was supposed to be defeated actually won, and the fanfiction could explore how that changes the entire dynamic of the story and the relationships between the characters.
You can start by checking out fanfiction websites like FanFiction.net or Archive of Our Own. Use the search function and type in 'Highschool DxD Volume 10' to get a list of relevant fanfictions. Then, look at the ratings and reviews to find the ones that are well - liked.
The Highschool DxD manga has gone a long way, presenting detailed plots and character developments. However, to know exactly how far it has gone, you might need to check the latest releases or related manga forums for the most up-to-date information.
The Highschool DxD manga has gone a long way, presenting exciting adventures and romantic elements. But as with any manga, its continuation and extent are subject to multiple factors like popularity and the creator's vision.