Will you, I pray, demand that demi-devil
Why he hath thus ensnared my soul and body?
– William Shakespeare
Othello, Act 5, Scene 2. Othello uses the metaphor of the devil trapping him soul and body in a snare to describe Iago’s scheming and entrapment of him. When he refers to Iago as a half devil, he is acknowleging his own role and responsibility for what has happened. Othello is talking to Cassio here.