The Wrong Man (слэш)

Jin Guanyao is in the Unclean Realm again, playing for Nie Mingjue. It should have been just like any other day but Nie Mingjue had been particularly cutting so Jin Guangyao gave the music a little extra push. After all, it would only make him a little sicker. In the grand scheme of things, it wouldn't really make a difference. Turns out, he was wrong about that.
Lan Xichen has had a brilliant idea on how to help both Nie Mingjue and Lan Wangji and he couldn't wait to share his plan. He has arrived unexpectedly in the Unclean Realm and Nie Huaisang is taking him to Jin Guangyao and Nie Mingjue. He hears the music. While it might only make Nie Mingjue slightly agitated, Lan Xichen is a Lan. They cultivate with music and so he is much more sensitive than most.
Lan Xichen hears the song from the Collection of Turmoil and he qi deviates. This changes everything.
As Lan Xichen's heir, Lan Wangji becomes Sect Leader. What difference will it make when Hanguang-Jun, the Light Bearing Lord leads one of the four great sects? What will happen when Lan Wangji has the power to change the world?