You guys like to talk some rubbish hey. Lucifer is a Latin name, a title actually. And Satan isn't a unique proper nouns, there are satans, a satan… satan means adversary.
Lucifer is known in other texts as Samael, and is an apportioned member of the Hand of God, sits by the high throne.
His role as defined by he whom we are told he rebelled against, was to be a Tempter of Man, to see who deserves return and who needs to be unmade.
He is doing exactly what he is supposed to be doing. You just… shouldn't want to side with the Adversary.
*according to, you know, texts.