Another place to check could be Tolkien - themed forums. There are often threads dedicated to sharing fanfiction. Members of these forums are passionate about Tolkien's works and might have written or know of some great Elrond and little Arwen fanfiction. You could also post a request there asking for any such stories.
One common theme is family bonding. Since Elrond is Arwen's father, many fanfictions explore their relationship, like Elrond teaching Arwen about their elven heritage or protecting her. Another theme is Arwen's growth. Writers might show how she develops from a little girl to the strong woman she becomes in the lore with Elrond's influence.
Emotional hurt is also popular. This could involve things like heartbreak, betrayal by someone he trusts, or the weight of his long - lived experiences and the losses he has endured over the centuries. It makes for some really deep and angsty stories.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you can search for 'Elrond hurt' in the search bar. There are likely to be many stories there that fit what you're looking for.
One characteristic is the strong focus on the relationship between the reader and Elrond. It often involves the reader being inserted into the Middle - earth setting and interacting directly with Elrond. Another is the exploration of Elrond's wisdom and power. Fanfictions usually show how the reader benefits from Elrond's knowledge. Also, there's often a sense of adventure as the reader and Elrond might go on quests or face threats together.
There's a fanfiction called 'Arwen's Choice'. It focuses on Arwen's decision to choose a mortal life for Aragorn. It's well - written with a lot of emotional turmoil and the way it shows her love for Aragorn is really touching. It also gives great insights into the elven culture in relation to love and sacrifice.
One idea could be that Elrond travels back in time to the First Age to prevent a great tragedy. He uses his knowledge and wisdom from the Third Age to change the course of events. Maybe he stops a powerful weapon from being created that would later cause destruction.
Finding Elrond and Bilbo pregnant fanfiction could be a bit of a challenge. In the Tolkien universe, Elrond is an Elf-lord and Bilbo is a Hobbit, and their relationship in the source material is more of an acquaintance or friendly connection. But in the world of fanfiction, anything is possible. Writers often like to take characters and put them in unexpected situations. So, while it's not a typical or widely - known type of fanfiction, it might exist. Try using specific search terms on fanfiction - dedicated websites and see if you can turn up any results.
One common theme could be forbidden love. Since Elrond is a significant figure, a 'lemon' fanfic might explore a relationship that is not allowed in the traditional lore. Another theme could be passion and desire, which are often associated with the 'lemon' aspect.