Paraphrasing my tumblr post from a while back:
Ironically enough, writing it made them take over my brain. I watched the show in late 2022 and had 1 (one) plot bunny one year later [What If I Stay?, my most-read BSD fic]. Despite shipping fictional pairings all my life, I didn't ship much of anything in bsd back then. I didn't pay "the popular bsd ships" any mind, looked at knkdz, and went, "yeah, they're haha funny, if I were to ship something it'd probably be this".
Writing that fic was only to get the idea out of my brain so that I could focus on other stories. It forced me into a deep dive in their dynamic. I was in-between fandom phases with other stuff at the time [MHA, Ace Attorney] and my newly found love for knkdz took over my life.

I've always been one to like "annoyer and annoyed" + "silly and serious" + "smart people who make each other stupid" + "undying trust despite the bickering". They check all boxes for things I've liked across the years, with the exception of being male/male.