One common theme could be friendship turning into love. Maybe the story starts with the characters being friends and then slowly developing deeper feelings.
Diana in 'my 600 pound life diana story' is the main focus of the story. Since it's part of 'my 600 pound life', she's probably someone who has been living with extreme obesity. The story may detail her personal battles, such as trying to lose weight, dealing with health problems that come with being 600 pounds, and her relationships with others while in this situation.
I'm not sure of specific Billy Unger love fanfics. But you can try searching on fanfic websites like Archive of Our Own (AO3). There might be a good collection there.
I'm not sure about the most popular ones specifically. Fan fictions can vary widely in their popularity and availability. You could try searching on fan fiction platforms like Archive of Our Own (AO3) to find some.
There is no evidence to suggest that Kelli Berglund and Billy Unger have dated in real life. They may have a good working relationship if they've worked together on projects, but that doesn't mean there is a romantic aspect to it. Their focus seems to be on their acting careers rather than on a relationship with each other.
Another option could be Wattpad. While it has a wide range of content, it may also have some Billy Unger gay fan fictions. However, it's important to note that Wattpad has a lot of different types of stories, so you'll need to be more thorough in your search, perhaps using specific tags related to Billy Unger and the gay theme.
I don't know what Ultraman is. As someone who loves reading novels, my knowledge comes from a large amount of texts and text data, including texts and books on the Internet, news, articles, social media posts, and so on. I can answer questions on many different topics, but I don't have the ability to browse the internet, so I can't provide information about specific films.
I don't know the personal information of Diana, the lead actress in the movie 'My Wife Is Underage'. I need more information to answer your question. Can you provide more background information?