For the brutally honest opinion on a ship meme: Yin Yu and Qi Ying
Hm this one is a hard one for me. I mean I do get the pairing but honestly, the way that Quan Yizhen is being portrayed in the book makes it hard for me to ship him in any non-platonic way tbh. If it was the modern world I would probably see him somewhere on the autistic spectrum, very focused on specific things (fighting) while being very very bad at parsing emotion of any kind. That does of course not mean that he could not have romantic feelings for anybody, just the way he feels to me is...idk, he is very innocent and naive in a way, extremely bad at understanding social clues/emotions ( I mean Yu Yin was NOT subtle about how much he loathed him) and I personally get more of an ace/aro-flavor from him. He sees Yin Yu as his Shixiong and I do not get any more of that from him tbh.
Doesn´t mean they´re unshipable to me, but it all depends on how Yizhen would be portrayed. I would need him to be a little bit more “mature” and less naive to not get a sense of their relationship being unbalanced that would throw me off. Yin Yu does have a mean, cruel streak and a bunch of issues on top of that, not to mention that he did want Yizhen to die, no matter if he regretted that later on. I would need Yizhen to be able to realize that up to a certain point and understand that his beloved Shixiong does have his darker parts too and that he needs to mind these so he doens´t end up getting hurt in the end.
And I don´t want Yin Yu to “give in” to Yizhen (who can be very forceful when he sets his mind on smth after all) just out of that bad conscience he has for how he treated him either.
So yeah, not per se a non-ship for me but it would need to be very well written and portrayed in a certain way for me not to feel uncomfortable around it. A little bit of “power play” as long as both parties know what happens and are okay with it is perfectly fine with me (the “yifu” thing in Sha Po Lang for example) but on the end I need my couples to be equally matched. And imho that could be a problem with YIn Yu/Quan Yizhen if you´re not careful^^