Fanon likes to portray Jiang Cheng and Lan Wangji as being jealous of each other because they fear wei wuxian will choose one of them over the other. Which is ignoring the fact that at least in novel canon Jiang Cheng did not even fucking know wangxian ever got along let alone that lwj was in love with wwx until at the very end of the story (in cql canon he does go through a wangxian phase early on and gets very confused by their "breakup" during wwx's sunshot era) and that Lan Wangji is mostly filled with loathing towards both himself and Jiang Cheng for 'abandoning' Wei Wuxian and not being able to save him.
It also ignores the much bigger point that both Lan Wangji and Jiang Cheng are actually jealous of Wen Ning. And why wouldn't they be? That is who Wei Wuxian chose in his first life. He left the Jiang, told Lan Wangji to fuck off no he is not coming to gusu with you, and spent his days with his little-brother-shaped corpse bestie on his mountain in yiling. And then when he came back he immediately called him up the second he could string together more than two notes on a flute. Wen Ning is the real competition. (And he's winning)
