Fanfiction.net is another popular site. There are countless Haruka and Michiru fanfics there as well. However, the quality can vary, so you might need to sift through a bit. But it's definitely worth looking into as there are some hidden gems among the many stories available.
You can start by looking on Archive of Our Own (AO3). It has a large collection of fanfictions, and you're likely to find many great 'haruka and michiru' ones there. Just use the search function and type in their names.
These two could be from a specific fandom. They are characters that the fanfiction author has chosen to focus on. Michiru's love for Haruka in a tux could be a unique take on their relationship. Maybe they are part of a group of characters in their original story, but here, the fanfiction delves into their individual relationship, with the tuxedo being a significant symbol of attraction for Michiru towards Haruka.
Social media platforms can also be helpful. Search for hashtags related to Haruka Michiru and fanfiction. You might come across bloggers or fans who have a list of their favorite fanfics and are willing to share them with others.
Some of the best Haruka and Michiru fanfics often explore their relationship in different settings. For example, there are fanfics that place them in modern-day high school scenarios, where they deal with typical teenage problems while still maintaining their unique bond. These stories can be really interesting as they give a fresh perspective on their characters.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of various fanfictions, including those related to Haruka x Usagi x Michiru. Just search for the relevant tags, and you'll likely find a good number of stories.
There's 'A Glimpse of Eternity' which is also quite good. It focuses on the more tender and private aspects of their relationship. The author does a great job of painting a vivid picture of their love and the small, everyday moments that make their bond so special.
In fanfiction, Michiru loving Haruka in a suit often plays into the themes of power dynamics and aesthetic attraction. A suit can represent power, and Haruka wearing one might make her seem more in control. Michiru, being drawn to this, could imply that she is attracted to Haruka's strength and the air of mystery that the suit adds. It also adds a layer of visual appeal, as the contrast between Michiru's more graceful style and Haruka in a suit can create a captivating dynamic.
It could be some of the old enemies from the Sailor Moon series who see the baby as a threat. Maybe the Death Busters, if they were still around, would want to use the baby's power for their own dark purposes.
There's also 'Haruka's Journey'. This fanfic focuses on Haruka's individual growth and how she overcomes various challenges. It's a great read as it stays true to her character traits while also adding new and interesting story elements.
One common theme is the exploration of their love. Since their relationship is a central aspect, the kiss often symbolizes the deepening of their bond. Another theme could be the secrecy or the acceptance of their relationship, as in some versions, their relationship might face challenges in terms of public perception or social norms.