Wei Wuxian could not have told you the last time he took any pain medication. It certainly wasn't available on the streets. When he was taken into Lotus Pier, Wei Wuxian had been afraid of using too much bath water, let alone using expensive pain medication. He often concealed injuries, something he got increasingly good at over the years. Turns out if you make a big deal out of completely innocuous injuries, it makes it real easy to hide bigger ones.

Then of course the war happened. Wei Wuxian had lost his golden core. He couldn't risk being treated by any of the doctors in camp. They'd discover his lack of a golden core easily. Which then held true for any injury or illness right up until he left the YunmengJiang sect and lived in the Burial Mounds. While Wen Qing made sure he got medical treatment, the reality was that their ability to get medicine of any sort was extremely limited.

Technically Wei Wuxian had opportunities to use pain medication. It wouldn't have been hard to get some pain medication along with some of the common ointments he kept in his quarters. Except that pain medication had in some ways become more terrifying than pain. Wei Wuxian lived in a constant state of alert for so long. Not trusting that someone or something wouldn't attack him. Not trusting that he might not lash out if he had a nightmare.

The few times Wei Wuxian remembered being given pain medicine, when he failed to hide a serious injury, it had made him drowsy and unfocused. To Wei Wuxian that meant being vulnerable.  Something he hadn't been able to afford to be. The concept of allowing it still brought a fresh rush of anxiety. So when Lan Wangji wanted him to take it Wei Wuxian had automatically tried to refuse.

It had taken that look of concern and hurt in Lan Wangji's eyes. That and the reminder that Lan Wangji wasn't going to leave him alone. Lan Wangji would not leave him vulnerable and alone. Lan Wangji would make sure he was safe.

The pain medicine had been very effective. It made getting the injuries treated much more pleasant. It also made him feel calmer. Wei Wuxian couldn't say how much of that was the medicine and how much of it was Lan Wangji's presence. It was hard to tell, especially when Lan Wangji was holding him in a warm embrace while running his fingers through Wei Wuxian's hair. Wei Wuxian practically melted under Lan Wangji's hands. He vaguely felt something soft and warm brush against his temple before his mind disappeared into a fog of sleep.

Wei Wuxian didn't wake until the following day. Technically it was only a guess that it was the following day, but by the accuracy of Lan Wangji's internal clock Wei Wuxian could assume his guess was probably correct. Lan Wangji insisted on checking Wei Wuxian's wounds twice a day. He had medicine to reapply, fresh bandages to change, and he insisted Wei Wuxian at least take medicine in the evening so that Wei Wuxian could rest properly. Wei Wuxian found it very endearing. He would have found it adorable, except that he saw the deep flash of pain in Lan Wangji's eyes every time he looked at Wei Wuxian's wounds. Wei Wuxian hated seeing Lan Wangji in pain.

"What injuries did you suffer when we killed the Xuanwu of Slaughter in your last life?" Lan Wangji inquired. It had become commonplace for them to refer to the future Wei Wuxian lived through as Wei Wuxian's first life, or previous life. It was not perhaps perfectly accurate in terminology, but it served its purpose well enough.

"Mn?" Wei Wuxian inquired in confusion. Lan Wangji was currently redressing Wei Wuxian's puncture wound.

"This creature is not the divine beast, Xuanwu, but it is powerful. A demi-Xuanwu." Lan Wangji spoke slowly as he organized his thoughts carefully. "The only record of such a creature is four hundred years old. It slaughtered countless people before going into hibernation. What injuries did you sustain?" Lan Wangji repeated his original question. Wei Wuxian's eyes widened with understanding.

"Lan Zhan, in my last life your broken leg was not yet healed and we had been stranded without food or water. We will do much better this time." Wei Wuxian said with a smile. Lan Wangji scowled.

"We will, because Wei Ying will tell me what we did and what injuries we sustained last time." Lan Wangji asserted firmly. Wei Wuxian tried pouting his way out of it, but this was not the sort of glare that Wei Wuxian could melt. This was one of Lan Wangji's, 'Your well being is more important than how cute you are,' stares. Wei Wuxian sighed in defeat.

"Last time you killed it with your clans Chord Assassination technique. You set up a formation with it ahead of time. I entered its shell. I'm not looking forward to that part. It likes to store things in there and doesn't seem to mind if it spoils." Wei Wuxian devolved into muttering, remembering the foul odour and putrid liquids he had to wade through.

"Wei Ying." Lan Wangji's voice was lightly scolding. Wei Wuxian grinned awkwardly, scratching his head.

"Right. So I was supposed to lure it out, which I did. We fought a little, and you decapitated it." Wei Wuxian announced brightly. Lan Wangji levelled an unamused stare at Wei Wuxian. Wei Wuxian wilted under the look. "I may have nearly gotten eaten, and caught a fever. It might have been because of the sword. I wasn't used to handling resentful energy back then." Wei Wuxian explained quickly.

"You are worried about the sword." Wei Wuxian deliberately looked somewhere else when Lan Wangji said this. "Wei Ying." Lan Wangji prodded.

"The sword is what I use to forge Yin Hufu. I used it during the war, when Chenqing and I were not enough." Wei Wuxian said quietly.

"It is the weapon people wanted to take from you." Lan Wangji said quietly. Wei Wuxian nodded.

"I... I don't want to forge it again." Wei Wuxian whispered. Lan Wangji set aside the materials he had been using to treat Wei Wuxian's wounds, then gently took Wei Wuxian's hands in his. Wei Wuxian glanced up at Lan Wangji. The light in Wei Wuxian's dark eyes was dimmed by fear and pain. It was a look Lan Wangji was familiar with, still appearing frequently when Wei Wuxian woke from his nightmares.

"Wei Ying. Tell me." Lan Wangji said softly.

"The sword that is in the Xuanwu of Slaughter's shell is soaked in resentful energy accumulated from the untold number of lives that the Xuanwu of Slaughter has taken. When I forged it into the Yin Hufu I thought it would be like Chenqing." Wei Wuxian began. "Chenqing channels resentful energy, much like your Wangji channels spiritual energy. Just like Wangji, Bichen, and Suibian, Chenqing acknowledges a master. Not just anyone can pick up Chenqing and start using it to control corpses."

"Yin Hufu does not do this?" Lan Wangji inquired. Wei Wuxian shook his head grimly.

"The Yin Hufu is incredibly powerful. More so than I had expected it to be, and it doesn't care who uses it. If you hold it in your hands, you can use it. A tool that lets anyone who picks it up control an army of fierce corpses." Wei Wuxian's voice was quiet. Lan Wangji noticed that Wei Wuxian seemed suddenly paler.

"You would never allow such an object to fall into the wrong hands." Lan Wangji whispered quietly. Wei Wuxian smiled weakly back at him.

"Allow, no. Except that I never found a safe way to destroy it." Wei Wuxian said quietly. "In my last life I destroyed it. I expected the backlash of it to kill me. It certainly felt like it was killing me." Wei Wuxian muttered quietly.

"That was when you woke up in the Cold Spring." Lan Wangji filled in. Wei Wuxian nodded.

"I don't mind using demonic cultivation. I don't like how people will react to it, but the worst part is over. I already went through the painful process of learning how to do it, and with that behind me it isn't a problem." Wei Wuxian stated firmly. "Yin Hufu... It's on another level. I know I can use it and manage it. I... I don't like it, but I did it before and can do it again." Wei Wuxian took a deep breath.

"The problem is what to do when the war ends. If I forge it people will want it. I can't risk letting anyone else wield it. The Yin Hufu absorbs resentful energy from around it unless you do something to prevent it. It can absorb amounts of resentful energy that even I might not be able to manage. During the war I was using it, which expended resentful energy. After the war I spent a significant amount of time cleansing large amounts of resentful energy from it and placing seals to prevent it from absorbing resentful energy of its own accord." Wei Wuxian explained nervously. "I..." Wei Wuxian stopped and Lan Wangji could see Wei Wuxian beginning to spiral. Lan Wangji picked Wei Wuxian up and placed him in his lap.

"I'm here, Wei Ying. You are safe." Lan Wangji whispered soothingly as he held Wei Wuxian in his arms. Lan Wangji could feel Wei Wuxian's erratic pulse and rapid breaths. "Slow your breath." Lan Wangji said calmly as he began to slowly brush his fingers through Wei Wuxian's hair. Lan Wangji deliberately took slow deep breaths. Wei Wuxian began to automatically match his breathing to Lan Wangji.

"Lan Zhan... Is it stupid to be afraid of a tool you made? A tool you plan to make again?" Wei Wuxian asked in a small voice.

"Wei Ying will never be stupid. Reckless, but never stupid." Lan Wangji said softly