tell me everything's not fine (слэш)

Jiang Cheng has at least seventeen other things he should be doing. Lotus Pier won’t manage itself, and the disciples need constant supervision or they start to slack. He should be on his way back already; his trip to Qinghe has already stretched several days longer than he had originally planned.
Instead, he’s standing in front of the sect leader’s quarters staring down an increasingly unnerved-looking servant.
AU where Jiang Cheng happens to be in Qinghe when Nie Huaisang learns the truth about his brother's death.