Well, the comic of 'A Business Proposal' often expands on certain storylines and gives more depth to the characters. But it also might have to condense some parts for the comic format.
Another theme is exploring the backstories of the characters more deeply. In the actual drama, there may not have been enough time to fully develop all the characters' pasts. Fanfictions can fill in those gaps, like delving into the character's family history or how they came to be the person they are in the drama.
One great Kdrama to watch for a love story is 'Crash Landing on You'. It tells the story of a South Korean heiress who accidentally paraglides into North Korea and falls in love with a North Korean army officer. The chemistry between the lead characters is amazing, and the show beautifully depicts their journey of love across different cultures and political boundaries.
Another place could be Wattpad. There are many Kdrama fans who post their fanfictions there. Look for the Snowdrop section or do a general search. However, the quality may vary, so you might need to sift through a bit to find the really good ones.
Strange World isn't a comic. Usually, when we talk about Strange World, it refers to a particular fictional setting or story that isn't presented in the comic book format. Maybe it's a part of a broader multimedia franchise, but not a comic specifically.
One common theme is unrequited love. For example, in many Kdramas, one character loves another deeply but that love is not returned immediately or at all. Another theme is separation due to external factors like family differences or social status. Just like in some dramas where a rich heir can't be with a poor girl because of family opposition.