There are many interesting fanfictions on this topic. Some might focus on how they deal with the pregnancy in the dangerous world of vampires and werewolves. For example, they could be facing threats from other supernatural beings who see their unborn child as a threat or a powerful asset.
Another theme is protection. Given the dangerous nature of their world, protecting the unborn child from various threats is often a central plot point. Enemies might try to harm the baby because of its potential power or to get revenge on Caroline and Klaus.
I'm not sure about a specific title that stands out above all others for TVD Klaus gay fanfic. However, if you search on platforms like Wattpad, you might come across some interesting ones. Some fanfics might focus on Klaus's character development as a gay vampire in relation to other characters from the show. You could also try looking at Tumblr blogs dedicated to Vampire Diaries fanfic. They often share and recommend good gay fanfics involving Klaus.
First, you need to really understand the character of Klaus from TVD. Know his personality traits, his backstory, and his relationships within the show. Then, create a male character that would be an interesting match for him. You can start with a simple plot, like how they meet and what draws them together. For example, it could be because of a shared goal or a mysterious connection. Also, don't be afraid to add your own unique twists to the Vampire Diaries lore.
Well, a possible plot is that Elena's pregnancy is the result of a spell gone wrong. Klaus, despite his initial shock, decides to stand by her. This could lead to a series of events where they have to fight off those who see the baby as a threat. It could also explore how Elena deals with the physical and emotional changes of pregnancy while being in a rather strange relationship with Klaus. And the baby might have some unique abilities that are both a blessing and a curse.
Their relationship would likely become more complex. Klaus, who is used to being in control, might become more possessive yet also more tender towards Elena. Elena, on her part, would have to rely on Klaus more, which could create a strange bond between them. They would have to learn to trust each other in a whole new way as they are now responsible for the unborn child.
One great 'TVD Caroline pregnant' fanfiction is 'Caroline's New Chapter'. It beautifully explores Caroline's journey through pregnancy while dealing with the supernatural world around her. The author does a wonderful job of portraying her strength and the support she gets from her friends.
Games that have no clear rules and are just a setup for chaos can also be dreadful. In certain TVD fanfiction, there are these so - called 'games' where different supernatural species are thrown together in a confined space and have to'survive' in a completely random and unfair situation. There's no real purpose to it other than to create a lot of mayhem and death, which can be off - putting for many readers.
One common theme is the struggle with identity. The OC, being pregnant, may question who she is now and how it changes her role in the TVD world. For example, is she still a fighter against the vampires or does the pregnancy make her more vulnerable and change her priorities.