I can't pick just one so have a few.

Drops of Gold Yungi, in a way. I have a couple of friends that are Yungi Truthers, and reading their fics just sort of cemented them together in my head, I guess? Originally, Drops of Gold wasn't supposed to be Yungisang, but in writing the entire going to the mall scene between Yunho and Mingi, I realized that I had been bitten by the Yungi bug and could not NOT write them together in some way. Their chemistry and the way they play off of each other is too good.

Shaded Topaz. They're a duo that I love to pieces because they have such an unlikely story. Hongjoong the demon hunter who couldn't continue doing what he was raised to. Wooyoung, the nightmare demon that was too curious about this strange human for his own good. The way they both care for each other in different ways. They're the couple that is bickering while laying all over each other and have no intention of moving. The ones where something is so off if they aren't near each other.

Shaded Jonggi. If you ask either of them about how they met each other, you'll get some variation of 'I picked him up as a stray in a dark alley' from both of them. They're just two stubborn men who seem so unlikely together, but have so much respect for each other. They understand each other in ways that other people can't or have a hard time with, and have no intention explaining themselves to others. I love being able to just play around with them and their eccentrics.

Circling Back To You Woojjong. It was the first time I had ever really considered Woojjong since Jongho is extremely difficult for me to grasp in my writing, and I went into the fic with no expectations. I ended up liking the two together more than I thought I would (even if I haven't really been able to write Woojjong since) and its a fic that has just stuck with me as one of my favorite oneshots. I hope one day I'll be able to write a good Woojjong again (maybe vamp wolp au, I haven't decided yet, but I do like how Sika and I have built the entire relationship)