You just retweeted something saying Childe is a villain
I can't control the wording of everything I retweet, the point of said tweet was make a comparison between the nature of a knightly proper 'bad guy's and the nature of a 'bad guy's knight that can be seen with Childe and Lohen, use your little head for once.
They are clearly referring to 'villain' as in part of the Fatui, who take a villainous role but will eventually be our allies against a bigger threat. Not that hard, I promise you.