Sun is frightened of Locke when they arrive at St. Sebastian's

In the flash sideways Locke is in an ambulance with a paramedic and Ben being rushed to the hospital. Ben tells the paramedic that Locke is a paraplegic, but he doesn't know anything else about him. Ben says that he saw the man who hit Locke and the paramedic says that he can talk to the police at the hospital.

Ben says he doesn't know who to contact for Locke, when Locke weakly says the name Helen Norwood. He also says that he was going to marry her. Ben tells Locke that he'll still marry her because he's going to be okay.

Once they arrive at the hospital, an ambulance carrying Sun and Jin arrives too. Sun and Locke are wheeled in right next to each other when Sun looks over and sees Locke. Sun freaks out, repeating "It's him!"

So it seems that Sun has had a vision of the original timeline, since she recognizes Locke and is afraid of him. It's all seems to be coming together now.