AO3 is probably the best bet. It not only has a vast amount of kyo x yuki fanfiction but also allows for various filters to help you find exactly what you're looking for. You can filter by rating, word count, and more. FanFiction.net is also a classic place to search. And don't forget about Tumblr. Some Tumblr blogs might share or even write their own kyo x yuki fanfiction, although it might be a bit more scattered compared to the dedicated fanfiction sites.
You can try some popular fanfiction websites like Archive of Our Own (AO3). It has a large collection of different fanfictions, and you're likely to find a good number of kyo x yuki ones there. Another option is FanFiction.net.
There are several places. AO3 is a great start as it has a well - organized tagging system for easy searching. Wattpad might also have some kyo x yuki fanfiction. Some smaller, niche fanfiction communities dedicated to the source material of Kyo and Yuki might also be a good place to look. Just make sure to follow the community rules when exploring these sites.
A practical answer is Chapter 76, because it turns the idea into a concrete scene. The chapter opens with Thinking of this, the aunt repeatedly praised, "Girl, hearing your words..., adds pressure through Leaving aside whether what she's made is good or not, just taking these..., and ends on Soon.
Chapter 53 is the strongest chapter-level answer because it starts from Night had fallen over Chixia Village, eerily void of any human sounds. and follows through on Wait, did this kid accidentally fall into the water?] [Help, this camera....
A practical answer is Chapter 55, because it turns the idea into a concrete scene. The chapter opens with Su Yinwan hadn't expected that, in just one day, Jiang Li's reputation had..., adds pressure through This person was even a top gaming streamer with tens of millions of fans,..., and ends on.
The best chapter pointer here is Chapter 54, "Acting Righteously Hits the Trending List Again!". It opens with Five minutes later, the people of Chixia Village, who had received the... and closes on She was also polite and friendly, and to top it off, she was good-looking,....
Chapter 28 is the strongest chapter-level answer because it starts from The next evening, Jiang Yan drove home seething with rage. and follows through on Lili then kicked his knee hard..
The best chapter pointer here is Chapter 55, "I Can Prove Everything Miss Jiang Said Is True!". It opens with Su Yinwan hadn't expected that, in just one day, Jiang Li's reputation had... and closes on He Yun's fans were immediately displeased..
The best chapter pointer here is Chapter 86, "If you don't welcome me, why should I stay?". It opens with After over an hour of fuss, it was finally time to eat. and closes on But then her expression became resolute and arrogant..
A practical answer is Chapter 64, because it turns the idea into a concrete scene. The chapter opens with Chixia Village lay in tranquil slumber., adds pressure through Is there really a need to put her down like this?, and ends on He'd been a host for so many years; he was used to it..
If you want the clearest chapter reference, go to Chapter 79. Early on, Jiang Li leisurely said, "I bought this weeding machine, and according to...; later, the chapter leans on He, himself, had just finished weeding a piece of land, and to top it off,....
Chapter 110 is the strongest chapter-level answer because it starts from Jiang Li, carrying a wooden basin, walked over to the well. and follows through on My parents died, and fortunately, Daddy found and took me in..