I really like 'Klaus and the Unlikely Companion'. In this fanfiction, the OC is a witch who crosses paths with Klaus. What makes it stand out is the way it portrays Klaus's vulnerability around the OC. It shows a different side of him that we don't often see in the show. The plot twists are also quite engaging.
The plot is crucial. It should be engaging and not just a rehash of the show's storylines. Maybe it could involve a new supernatural threat that Klaus and the OC have to face together. This gives an opportunity for character growth and development of their relationship. Additionally, the writing style matters. It should be easy to read and flow well, with good dialogue that captures the essence of the characters.
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.
A theme that frequently shows up is redemption. Klaus, being a complex and often villainous character, may be on a path to redemption in some fanfictions, with Stefan either helping or hindering. Also, power dynamics play a role. Klaus is very powerful, and Stefan has his own set of abilities, so how they interact in terms of power is a common theme. For example, in some stories, Stefan has to find ways to level the playing field when dealing with Klaus.
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.
You can find 'Stefan and Klaus fanfiction' on popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of fan - created stories with various themes and ratings related to different fandoms, including this one. Fanfiction.net is also a good place to look. It has been around for a long time and has a wide range of stories.
One great 'Stefan and Klaus fanfiction' is 'The Bond Beyond Enmity'. It delves into how their complex relationship could develop in unexpected ways, like finding common ground in protecting Mystic Falls from a new threat. Another is 'A Different Alliance' which explores a scenario where they team up for a personal vendetta against a more powerful enemy.
He could be very protective. Klaus has always seen Caroline as someone special. Now that Stefan is gone, he might feel a stronger urge to keep her safe. He may try to show her that he can be a better option for her than Stefan ever was, not in a mean way, but out of his own feelings for her. He'll likely be very gentle at first, trying not to spook her.
There's a fanfiction called 'Shared Secrets'. In this story, Klaus and Stefan find themselves in a situation where they have to share their deepest secrets to survive. It's really interesting as it shows a more vulnerable side of both characters. And 'The Unlikely Alliance' is also good. It starts with a small encounter that gradually leads to a big adventure where they rely on each other.