Prim... had no real desire to meet Tim. Tim was a mentor. She didn't know many tributes, and there was no reason for him to try and influence him - and he sort of seemed creepy to her... And. Well. She was there for the tributes.

Besides, he might report her being there to Katniss. She'd snuck out of the house without permission, not actually expecting to see her sister on the ship. She should have remembered that Katniss, as a former victor, was a mentor with new charges and responsibilities... Of course she would do her best to serve them, no matter what it cost her personally. It was just who Katniss was.

Regardless, she came to a pause beside Tim, hands to the side of the yellow dress she'd picked out. "Hello," she offered him.