
Emilia can accurately be described as the least jejune character in Othello. She is inherently deep and metaphorical but, is she conniving? I can assure you, there is no definite answer to this question cited in the text, so it is up for us to speculate. My original predilection - deep down she knows about Iago's plan, but is unwilling to admit it to herself.
Some people describe Emilia as sinecure, turning the other cheek to Iago's to benefit her own status, but I don't agree. I think she doesn't want to believe there is a malevolent side to her husband that she was blind to before. Emilia is not used to the evil side of Iago, and is a neophyte when it comes to plotting lies and murder.
In an attempt to retain the camaraderie she enjoys with Iago as husband and wife, Emilia does not warn anyone about Iago's plan when she finally allows the pieces to fall into place. Finally realizing she will be bereft of happiness if she keeps up the lie, Emilia finally confesses to Othello and a room full of Venetian soldiers. Emilia was not granted impunity, however, because Iago stabs and kills her as she finally tells the true.
So did Emilia know? In the back of her mind, yes. In her willing consciousness, no - not until the very end of the play.


