Dramatic Irony
Letting the audience know something a character doesn't. You watch them act without that knowledge, which creates suspense, dread or dark comedy.
Blue Steel
You know Hunt is the killer, but Turner does not. Their dates and conversations are tense because you want to warn her. Every sweet moment between them is a threat.
Hit Man
You know Ron is really Gary, a college professor, but Madison does not. Every kiss and every gun lesson plays on that gap. You watch her trust a man who does not exist.

