A different kind of cultivator

Poor Lan Zhan! I'd imagine that Wei Ying would stick by him and try to help guide him to properly use demonic cultivation, as he is the one who started the theory of using such skills, unless Lan Zhan started that theory in this story. Then is Wei Ying the uptight righteous one? Either way, I think Lan Zhan would think himself unworthy of Wei Wuxian and would never tell him his feelings. I think What happened during the Phoenix Mountain hunt would go about the same way as cannon, but Lan Zhan would get angry on Wifi's behalf leaving Wei Ying to try calming him down, maybe leaving with him during the banquet so they find Wen Qing and they both decide to help her and the Wen refugees. Unsure how the rest would go but I think Wei Ying would discreetly involve the Yunmeng sect to help while openly defending Lan Wangji's actions. 
Romance would be all the more heartbreaking because of Lan Zhan's self doubt and Wei Ying's oblivious but still cares, then maybe something like their first time together in book and Lan Zhan tells Wei Ying to "Get Lost," cause he thinks Wei cannot return his feelings or he comes to and thinks he had raped his beloved and runs away/kills himself in shame. Wei Ying follows/grieves.