I would recommend 'A New Beginning for Kaneki and Hide' which can be found on Archive of Our Own. It has a unique take on their relationship, exploring what could happen if Hide had a more active role in Kaneki's transformation journey. It's full of emotional moments and great dialogue.
One popular theme is friendship - turned - romance. Given their close relationship in the original Tokyo Ghoul story, many fanfictions explore how their bond could develop into something more romantic over time.
You can try searching on fanfiction websites such as Archive of Our Own (AO3). There are often many different fanfictions about various pairings, including Hide x Kaneki. Just use the search function on the site and type in 'hide x kaneki' to see what comes up.
Often, there are themes of protection and support. Given the unusual situation of mpreg, Hide might be portrayed as being very protective of Kaneki. And also, themes related to the acceptance within the Tokyo Ghoul world or their own small community could be present. Since it's an unconventional concept, how other characters react to it can be an important part of the story. Additionally, themes of love and sacrifice might be emphasized as they face difficulties together because of the mpreg situation.
Finding specific Kaneki x Hide mpreg fanfiction can be a bit tricky. Firstly, not all platforms may support or have a large number of such niche fanfictions. However, AO3 is a great place to start. Use the search bar and type in 'Kaneki x Hide mpreg' and it will show you relevant works. Keep in mind that the availability might vary depending on the popularity of this particular pairing and concept within the fandom.
Archive of Our Own (AO3) is a great place to start. It has a large collection of 'kaneki x hide fanfiction' with different themes and writing styles. You can easily search for what you like using the tags.
One idea could be a post - apocalyptic scenario where Kaneki and Hide are trying to survive in a world that has become even more hostile to ghouls. They could be on a journey to find a safe haven, relying on their deep - seated friendship and Hide's unwavering loyalty to Kaneki. Along the way, they face various challenges that test their bond.
Their relationship could be developed in a unique way by having Hide become a ghoul. This would completely change the power dynamic between them and force them to re - evaluate their friendship. They would have to learn to understand each other from a new perspective, as Hide now experiences the same struggles as Kaneki.