A/N: Takes place around 3x17 – Catch 22.
Manipulation
She doesn't trust Juliet. She doesn't trust any Others so why would she trust Juliet (she doesn't buy Jack's "she's one of us" speech)? She knows how much Ben can manipulate so why can't Juliet (there must be an Others 101 – How to Manipulate).
Kate's positive that she's manipulating Jack, telling him things that aren't true, making sure he'll stay away from her (Jack only spends time with her when he can't avoid it). She knows it could be just because she broke her heart but it's just the way how they're always sitting in a distance, talking to each other... it bothers her.
One day, Kate's going to show that Juliet can't be trusted (and maybe then Jack will see how she manipulated him).