Seeing Kate
Episode 5x2, The LieSun meets Kate and tells her that she has to do whatever it takes to keep Aaron safe. She says the men that came to see her were not interested in exposing the lie, they want Aaron. She also says she doesn't blame Kate for Jin's death.
The Package
Episode 5x4, The Little PrinceSun stays with Aaron in her hotel room while Kate goes to meet with Dan Norton. She receives a package and opens it to read surveillance information on Ben and Jack. Also in the package is a box of candy that hides a pistol.
Sun goes to the marina with Aaron and takes out the gun.
Proof
Episode 5x5, This Place is DeathSun leaves Aaron in the car at the marina and points a gun at Ben. She tells Kate to move away and Kate asks what she's doing and where Aaron is. Sun tells her he's in the car and Kate goes to get him. Sun tells Ben that he killed Jin.
Ben says he didn't kill Jin and neither did anyone else. Jin is alive and he can prove it. Sun and Jack go with Ben. On the way Jack says that if Sun doesn't shoot Ben, he will because of what Ben did to Kate. Ben slams on the brakes and tells them that if they knew what he has been doing to keep them and their friends safe, they would never stop thanking him.
He takes them to a church and gives Sun Jin's ring. He tells her that Locke gave it to him and Jin gave it to Locke. Sun wants to know why Locke didn't tell her himself and Ben says he doesn't know, but that maybe he didn't have time before he died.
Sun follows Ben into a church.
The Flight
Episode 5x6, 316Sun finds Jack at the airport and asks why he's surprised to see her. He says that he was afraid she would change her mind and she says that if there is any chance that Jin is alive, she has to get back to the island.
During the flight, they see the light and hear the hum.
