Very minor characters. They were the housemates of Kim Pine during Book 1 through Book 3 and she hates them all. Early in Book 4 Kim moves out to live with Hollie and Joseph. Sara appeared near the beginning of Book 2 showing that she's hates her as much as Kim hates her. She also attended The Clash at Demonhead concert near the end. Emily appeared at the concert with Sara but her info box said "I don't know this girl." Tracy appears as a stoner but never appeared in the books.
All three appeared in the short comic The Wonderful World of Kim Pine.