It could be that the name 'Birdsong' symbolizes something important in the story, like freedom, nature, or a particular emotion associated with birds. Or perhaps the author was simply inspired by the beauty and melody of birdsong.
Another theme is self - discovery. As they interact in the fanfictions, both Otis and Ruby often learn more about themselves. For example, in some stories, Ruby discovers a more sensitive side of herself through her interactions with Otis.
I'm not entirely sure which 'Otis' in 'Chicago Fire' specifically you are referring to. There might be different characters named Otis in various stories. But generally, in a love story within the context of 'Chicago Fire', it could involve a firefighter named Otis falling in love with someone. Maybe it's a fellow firefighter, or someone from the community they serve. It could be a story of them meeting during a rescue operation, gradually getting to know each other, and then developing deep feelings over time.
Another theme can be self - discovery. As they go through various situations, both characters might learn more about themselves. For example, in some fanfics, Otis discovers his hidden courage when he's with Lemon. And Lemon might find out new aspects of her personality while facing challenges with Otis.
I'm not entirely sure if there is a large quantity of Olympia and Otis kiss fanfiction. It really depends on the fandom. Some fandoms have a huge amount of fan - created content while others are more sparse. You could also check out some dedicated fanfiction forums where fans might share their works about Olympia and Otis kissing.