Recommendations

Both are school setting BLs with an unexpected endgame pairing.
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Both are very short, vertically filmed love stories with a café setting and a similar sweet vibe between the couple.

they tell similar stories, the ridicilous, comedic and cliches of bl series. In Zettai Bl, main character is in a Bl world but in Fudanshi Bartender, main character is a fudanshi

Both are BL cohabitation dramas that feature a actor that desires to get close to his reserved and reluctant housemate.

I loved 2gether, it was my first BL and despite later on seeing people point out valid criticisms, Utsukushii Kare managed to avoid those faults.

Utsukushii Kare is one of the best portrayals I've ever witnessed in BL or media itself of yearning, that concept which I was attracted to in 2gether. The chemistry feels so realistic and relatable but in its BL setting which lets it shine fully in fiction.

I don't want to spoil so I won't be specific but the aspects of pining, shyness, love & affection and the question of its reciprocation (or lack thereof), yearning, even arguably "tsundere" attitude, and more are absolutely top-notch here.

In both BL dramas one of the couple's is between one regular person (whom is known for his great personality) and his very obssessive fan.

In Secret crush on you the obssessive guy feels a bit more disturbing.., but harmless towards the guy he lies.. In History 4.. the obssessive guy is shaming and not that harmless.. he is also a step-siblimg to the guy.

I think they've got the same storyline. Tells about the importance of communication in a relationship.

Plot differs as HNH is about comic writers whereas, RH Plus is about vampires however, they are very similar in terms of the relationship between characters and both are family centred mainly brothers raising, supporting and protecting each other.

Two drama has similar plot lines
the male lead getting into a trap and get prison time for something he didn't do
trying to escape and prove his innocence is the goal in both dramas

fun and cute love stories. very little angst in the stories. adorable moments of affection. the stories relationships start sour but ends well

Both are lighter historical dramas with a contract relationship between the main couple.
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Both MLs have a false identity/secret and are married to the cheerful FL who is of lower social status. The main couple are initially indifferent to each other, but soon fall in love.

Both dramas have the ML with a false identity/secret that he uses to investigate an old case and find the truth about the past. FL is of lower status than the ML. Both are lighter dramas.

Both are historical mystery/romance dramas with a slow burn love story between the couple. Both dramas have a similar lighter tone.

Both are light-hearted with some more serious moments, mystery/romance hybrid genres, and have an initially semi-antagonistic to frenemies to friends to lovers relationship between the main couple.