Wei Wuxian is doing an experiment. He is doing an experiment to see whether fierce corpses maintain skills from their previous lives, and he's doing this experiment on the corpses of a few of the concubines from a minor branch of the Wen clan. If asked, he would say this is because he wants to see them dance sexily. In reality, it is because they were used by some ill-disciplined soldiers from the minor clans before being killed, and this built up a nice healthy amount of resentment so he knows that it's not just that they're too weak.
(The disciplines of the major clans would never rape the concubines. This is not because the Wen-dogs don't deserve it-- they deserve everything they get-- but because a major-clan disciple wants to marry a woman with strong cultivation who can handle her own sword in a night-hunt, and if you come to the marriage bed without your virginity intact she's liable to cut your balls off.)
Wei Wuxian is doing a second experiment. This experiment is on how long a person without a golden core can survive getting all of their calories from alcohol. It has been three days so far, which is a personal best.
Wei Wuxian keeps a few of the prettier and more resentful corpses, as research assistants, before sending the rest into battle. He can control them as easily as he can control his own hands. There's very little difference, these days; his hands feel like they belong to someone else.
His vision is blurring and wavering in front of him. He needs to learn how to see through the fierce corpses' eyes, he thinks, so he can keep working.
Wei Wuxian likes working, because when he's working he's not thinking, and nothing good at all comes of thinking. When he thinks, sometimes, he remembers things that happened before the war. He remembers nothing from before he came to the Jiang clan, which is a mercy, but his mind has not been so kind to him about afterward. He remembers swimming at the Lotus Pier, being the best at talismans and swordfighting and the dizi and everything else you put in front of him, nighthunts with Jiang Fengmian, sneaking into the kitchens to beg soup from Yanli, being whipped until his skin peels off because of thus-and-such infraction that was really Jiang Cheng's fault, and every single one of those happy memories has over it the tarnish of never again never again never again.
When he is luckier, he remembers the Burial Mounds instead, the hands grabbing at him and snatching bits of sleep when he can and the taste of a half-rotten leg. He doesn't like eating anymore. No matter what it is, it always tastes like corpse.
When he is very very lucky, he remembers the searing pain of having his golden core removed. But that's all right; it was for Jiang Cheng, and if nothing else Jiang Cheng is okay.
Wei Wuxian is not sure what day it is, or in fact if it's day rather than night. He rarely leaves his tent. Sometimes someone tells him that it's time for battle and he leaves his tent and pulls out Chenqing and begins to play, and this is the only time he's happy, a fierce radiant destructive joy. Instead of two hands or six he has a hundred a thousand ten thousand, and every one of them is devoted to one goal and one goal alone, destroying each and every one of those Wen-dogs, torturing them and making them hurt the way that everyone he loves was hurt.
He doesn't see Yanli, because she'd worry. He doesn't see Jiang Cheng, because he wouldn't understand. After the war is over, it will be all right. They'll be the Twin Prides again and they'll rebuild Lotus Pier until it was greater than it ever was before, and he won't have to work and there will only be happy things behind his eyes and he will eat Yanli's food until instead everything tastes of lotuses.
For right now, he drinks, and he works, and he waits until he is ready to kill.
And then the earth opens up under him.