Haru does love Legosi in the manga. It's evident in the way she cares for him, shows concern, and their shared experiences strengthen their bond, making it clear that her emotions towards him are those of love.
Sure, Legosi and Haru do get together in the manga. Their relationship develops over time, facing various challenges but ultimately finding their way to each other.
The 'redemption arc' trope can be seen in some 'legosi x oc fanfic' too. Maybe the OC has a troubled past or has made mistakes, and Legosi is there to support them through their journey of self - improvement. It gives a sense of growth and positive change in the relationship between Legosi and the OC. There's also the 'mystery OC' trope where the OC has some secrets that Legosi gradually uncovers as the story progresses, keeping the reader engaged.
Well, another place to look for 'legosi x oc fanfic' could be Wattpad. There are a lot of fanfic writers on Wattpad who write about different anime and manga pairings. Just use the search function and type in 'legosi x oc fanfic'. However, the quality might vary, so you may need to do some sifting through the results.
One common theme is friendship. Given their different species in the Beastars world, their friendship is often explored. For instance, how they support each other despite the initial prejudices. Another theme could be growth. They both grow as individuals, and their relationship helps in that process. For example, Haru might help Legosi become more confident in his own skin, and Legosi might teach Haru about the importance of self - defense in their dangerous world.