One common theme is the struggle for acceptance. The OC daughter often has to deal with Klaus's complex personality and the whole vampire - werewolf - witch world she's born into. Another theme is family loyalty. Despite the challenges, she usually shows great loyalty to Klaus and the rest of the Mikaelson family.
Well, Tumblr can be a good place too. A lot of fans post snippets or links to their Klaus Mikaelson OC daughter fanfictions on their blogs. You might have to do a bit of digging, but it's worth it. Some of these Tumblr fics are really creative and offer unique takes on the relationship between Klaus and his OC daughter.
Another plot could be that she time travels to a future where something bad has happened to her family. She then has to figure out what went wrong in the present to cause this future and work on changing it. For instance, if in the future Klaus and Caroline are no longer together and their family is falling apart, she could go back and try to prevent the events that led to this.
In the comics, Klaus is not immortal. He may have certain powers and abilities, but there are limitations and factors that can pose a threat to his existence.
In some comic versions, Klaus is indeed depicted as gay, with storylines exploring his romantic relationships with same-sex characters. However, this can vary depending on the creative team and the direction of the story.
Klaus isn't gay in the comic. The creators have not developed his character along those lines. The focus of his portrayal lies elsewhere in the narrative.
Klaus is not based on real events. It's a work of imagination that brings together various fictional characters and plotlines to form an enchanting narrative.
To be honest, it's not straightforward to say if Klaus is gay in the comics. It could depend on how you read between the lines or the subtext, but there's no clear-cut indication.