There's 'Yuji and Nobara: Unseen Connections'. This fanfic delves deep into their friendship that could potentially turn into something more. It has some really interesting scenarios where they rely on each other's strengths and learn from their weaknesses.
Often, they highlight their shared love for food. Since they are both in the culinary world in the original story, fanfics usually revolve around cooking challenges they face together or how they teach each other new techniques.
One common theme could be friendship. Given the nature of the characters in 'inu x boku ss', the fanfics might explore the deepening of friendships between the characters. For example, Nobara and other characters might have storylines that revolve around how they become closer friends and support each other.
One common theme is the discovery of love. Takumi and Megumi often start as friends or acquaintances and gradually realize they have deeper feelings for each other. Another theme could be personal growth. Through their relationship, they both learn more about themselves and become better individuals.