Katherine fights with Stefan but she didn't have feed enough blood from days because of being locked up in that cave so she wasn't that strong at the moment.
Stefan pushes Katherine away and takes a step backward because he might have chances to win but he doesn't want to waste his energy on someone like Katherine.
"See Katherine, he was a vampire and sealed up for more than a thousand years...he had no chance to save us...save you" Stefan explains to Katherine.
"Bullshit...he was a wonderful leverage to clear all of my messes and finally get rid of Klaus" Katherine says and throws Stefan towards the barrier thinking he won't be able to pass it but surprisingly Stefan passes the barrier and comes out of the cave.
Stefan was surprised by that and Katherine sees that as her chance of escape and runs with vampire speed towards the exit of the cave but Elijah comes in front of her and blocks her way out.
"Where do you think you are heading Katerina?" Elijah says blocking her way.
"Elijah!" Katherine says with fear.
"How I was able to pass the seal?" Stefan asks.
"I've had spell lifted...lovely Elena and I have come to a deal," Elijah says and takes a step forward towards Katherine.
"You are not going to act until I say so and will not leave this place...because when Klaus will come...he will wanna know exactly where you are, " Elijah compels Katherine.
Stefan seeing this opportunity asks Elijah about Ansel "Hey do you have any brother named Ansel?"
Hearing his brother's name Elijah gets surprised and questions Stefan" How do you know about my brother?... He's been dead from a thousand years".
"You told him about Ansel?" Elijah then questions Katherine.
"Actually, He's not dead" Stefan's words provokes Elijah and he grabs Stefan's neck.
"I might have made a deal with Elena but it didn't mean I won't hesitate to kill you or anybody," Elijah says angrily.
"Long blond hairs...blue eyes and almost six feet tall...he's not dead...he told us that he was sealed by your father thousand years ago," Stefan says while trying to free himself from Elijah's hold.
"Where is he?" Elijah asks keeping his anger on the face.
"He went toward the forest...might not have gone too far, " Stefan replies and Elijah lets him go.
"Remember Stefan...if I found out that you are lying then I'm going to kill you for this" Elijah said and left.
Seeing Katherine isn't trying to come out, Stefan leaves before Katherine says something.