(Wei Wuxian's fear of dogs is canon,by the way.)

Wei Wuxian got adopted by the Lan clan when he was 9,instead of the Jiang clan.But instead of being a disciple,he was a servant because of his parent's pasts.

Wei Wuxian doesn't have much memories of his parents,just a simple blurry moment of him walking through a forest with them when he was 5.

Wei Wuxian is a servant of the Lan clan.He wore white robes just like a Lan clan disciple,but everyone knows he's a servant.

The Jiang clan/family didn't yet meet Wei Wuxian.

Lan Wangji was writing in the library per usual and Wei Wuxian was sitting next to him silently with eyes staring down at the floor.

(You're Wei Wuxian.)