AUGH AUGH AUGH AUGH [sounds of me dying the longer I go without writing about the mad scientist AU]
Nie Huaisang has just received a message written in blood via a crow that does NOT look alive, likely from Wei Wuxian due to the reference of what his sect is like, similar to how he first approached Nie Huaisang with a message. He isn't quite sure what to do - he should go to his brother at least with this information, but he is very busy planning the war with Lan Xichen and Nie Huaisang doesn't want to cause any more stress for them. So! He instead goes to Lan Wangji, who is, as always, helping out in the medical tents whenever he's not on the battlefield. Instead of saying anything that could draw attention to the situation, Nie Huaisang just waves him over and then shows off the yin filled - almost definitely dead - crow, before gesturing for them both to leave the medical tent. Lan Wangji goes without question.
Nie Huaisang shows him the message and is like "so uhh I'm pretty sure this is from Wei Wuxian." "Why is it written in blood?" "he's in the Burial Mounds, you can't expect him to have ink." Lan Wangji concedes this point, and wants to know why he is being told this, so Nie Huaisang explains that to have a batshit insane Wei Wuxian on their side would be very damn useful. Issue is, they need to find the Wen siblings and Xue Yang and get them to safety in order to get his support in the war, and Lan Wangji is great for field missions during this lull in the fighting. It's not like Nie Huaisang is going out!! He works best behind the scenes, after all.
Of course, Lan Wangji is more than desperate to make up for the mistakes he made by not attempting to help Wei Wuxian when he first had a chance to, so he goes out of his way to hunt for the Wen siblings and Xue Yang, chasing down information in a way that is basically like what he was doing during those three months in canon. He finally learns that they are in the supervisory office of Yiling, and goes on over there to collect them - and take back Yiling in the process. Yes, there is a thought of how close Wei Wuxian really was to his family all along, but it's overshadowed by the realisation that they need to explain to Nie Mingjue and Lan Xichen what's been going on while they've been busy plotting and planning to save the Jianghu.
Lan Wangji makes the executive decision to bring it up during a meeting, and there is varying degrees of skepticism to the news. Nie Mingjue and Lan Xichen are open to the chance of a changing tide in the war, plus they owe Wei Wuxian the protection of his family after they so carelessly overlooked him before he was thrown into the Burial Mounds. Jin Zixuan is like "I said right from the start that he was brainwashed, but nobody believed me!" so he's willing to take the risk of harbouring three wen associates if it means being proven right through the powerhouse that could be Wei Wuxian. (I should explain that they believe that he must be pretty powerful right now because one, he's actually survived in the Burial Mounds, and two, he's had previous work with resentful energy, he had to be getting up to some kind of work in the hellsite.)
Jiang Fengmian is like "I don't know all that much about him, but he did save Jiang Cheng's life, and he's the son of my bestie" but Yu Ziyuan (who is obviously there because why wouldn't she be) is NOT having it. Why would she? She's a hater. She's saying all sorts of insults n shit, but Lan Wangji basically left the moment he got assent from all of the actual sect leaders, so it's all for naught in the end. Lan Wangji is too busy showing up to the supervisory office in Yiling with a small group of soldiers, kicking ass and taking names like there's no tomorrow. Xue Yang, who is quite rabid at the moment, is watching the carnage and being like "I'm going to fucking kill anyone who touches Wei-gege's notes" while Wen Ning and Wen Qing are getting ready to escape. Lan Wangji catches them in the act but is like "we're here to help" and shows them the note that the crows sent.
The lads (Wen siblings + Xue Yang) realise that Wei Ying is alive and go through so many different emotions but they don't have time to unpack all of them - Xue Yang wants to go into the Burial Mounds himself to collect Wei Ying, but Wen Qing shuts that down. They don't know how Wei Ying survived, and they have no clue if Xue Yang would survive. It's best to just let Wei Ying come back to them, like a stray puppy. Xue Yang does not like this, so Wen Qing instead gets him with a needle and Wen Ning carries him along, used to this turn of events. (Yes I have decided that Wen Ning is the shy but sweet brawns to his older sister's brains. He's not not smart or anything, I just think it'd be neat.)
Meanwhile, the crows are watching all around because they're in Yiling, and they report back to an anxiously awaiting Wei Ying, who has been pre-emptively gathering an army of resentful spirits who could find closure in fighting and violence and death. He's helping them all be chill through a gentle melody session, and the Burial Mounds is dragging more spirits into Its grounds to help out Its precious son! Wei Ying learns that his family is not only alive but close to him, and is simultaneously kicking himself while also thanking the Gods that they are alive and they're going to be safe in the grasps of the Sunshot Campaign. With that knowledge handed to him, he feels a lot calmer as he squares his shoulders, pushing all the pain to the side and focusing on the army of resentful spirits he has created.
Oh, the Wen won't know what hit them.