Typical characters would include the otaku themselves. They are often portrayed as passionate about their specific areas of otaku interest, whether it's collecting anime figures, being a huge fan of a particular manga series or spending hours gaming.
One common theme could be the struggle of otaku to balance their love life with their otaku interests. For example, they might face difficulties in finding partners who understand their love for anime, manga or games.
Common themes include the challenges of dating as an otaku. In 'wotakoi love is hard for an otaku' fanfiction, you'll often find stories about how the characters deal with their partner's otaku interests or how they try to introduce their own interests. Social awkwardness related to being an otaku in a relationship is also a frequent theme. It's about how the characters navigate the world of love while being deeply involved in otaku culture.
Yes, it can be quite popular. 'Wotakoi: Love is Hard for an Otaku' has a unique premise that attracts a lot of fans. Fanfiction based on it allows fans to explore different scenarios and relationships within the otaku - centric world that the original work presents. It gives them the chance to further develop the characters or create new storylines that they might have been thinking about while watching or reading the original material.