Love and unrequited love are common themes. Since mob has feelings for tsubomi, many fanfics explore how he deals with those emotions. Another theme could be growth, like how mob's relationship with tsubomi affects his personal development.
Well, you can try searching on fanfiction platforms like Archive of Our Own. There might be various mob x tsubomi fanfics there. Some could be about their relationship development from a friendship to something more. Just use the search function and look for tags related to them.
The relationship between 'Cartoon Guru' and 'Bhole' in Hindi could be anything. It could be a mentor-student bond, a sibling-like connection, or even a completely unexpected dynamic that is revealed as the cartoon progresses.