Who is Croy from Uglies and what is their importance?

Croy is a friend of Shay's who was part of a group of kids who left for the Smoke in the months before their sixteenth birthday. Shay was supposed to leave with Croy's group, but she chickened out at the last minute. Croy is suspicious of Tally from the moment she arrives, often questioning her claims of having made the trip in an exceedingly long nine days rather than five. When Croy sees that Tally has tried to escape the Special Circumstances agents on the day they invade the Smoke, he begins to believe in Tally's innocence until she admits her guilt to David weeks later.