Demas is mentioned in three of the canonical Pauline epistles:
Demas is also mentioned in the non-canonical Acts of Paul and Thecla, where he is described as holding views similar to the author of Second Peter. Based on this, Dale Martin speculates that whichever one of the Acts of Paul and Thecla and the Pastoral Epistles (including Second Timothy) was written later may have been arguing against the other.
In The Pilgrim's Progress, John Bunyan writes of Demas, a deceiver, who beckons to pilgrims at the Hill Lucre, urging them to join in the supposed silver mining being carried out there. Interestingly, Demas is described in Pilgrim's Progress as a fellow pilgrim, just like Paul describes Demas as a "fellow worker." In Pilgrim's Progress you can also see that he has a love for early treasures caused him to desert the path and could lead to his death just like Demas's love for the world caused him to stop following God, and eventually lose his salvation.