In the German legend of Faust. Mephisto was the devil who an alchemsit named Faust sold his soul to, hoping to gain knowledge and power.

A buzz word being used to refer to creators and influencers forming or encouraging unhealthy relationships with their fans. Usually used in the context of young audiences feeling they have a relationship with the influencer due to the huge amount of the influencer’s content they consume. The influencer in question, however, is unaware of the fan’s existence other than the general knowledge of having fans. Common examples include Dream and his stans. These relationships are exacerbated by the influencers confirming they have more than a creator-to-viewer relationship.

The word is circulating due to various YouTube essays about the phenomenon using the word, and therefore people who enjoy complaining about influencers repeating what they heard in the video in any comments section they can find.

That old Mephisto, the one who watches you as you sleep and clicks ancient murmurs in your ears. Constantly plotting, stalking, and breathing on helpless infants at night, his will is to be fulfilled. Be not too hasty to call his name, for he is always listening.

Mephisto is short for Meph·is·toph·e·les
Pronunciation: "me-f&-'stä-f&-"lEz
Function: noun
Etymology: German
: a chief devil in the Faust legend
- Me·phis·to·phe·lian /"mef-&-st&-'fEl-y&n, m&-"fis-t&-/ or Me·phis·to·phe·lean /same, or "me-f&-"stä-f&-'lE-&n/ adjective

Fallen Archangel.
Was the apprentice of Michael and was going to be lord of heaven, but lost it to Jesus because of the fall. Some say he left by himself and was not driven out.
Now he is The Duke of Hell, The Judge of the Damned, Lord of Fear and Nightmares, second only to Luciferin the hierarchy of hell

The lord of the wrecking.

me, the lord of pain.