Maybe it's a Meaningful Name, in the sense that the person has to have a cold heart in order to commit this kind of betrayal against one's friends or organization. Or perhaps it's a more subtle version of Evil Is Deathly Cold in works where outlandish ice outfits and frozen-over human skulls don't make sense. It might be a leftover from Cold War (har) era spy fiction — Siberian winters and all that. In any case, if there's a molehunt about to go down and someone on your side has "Frost" or "Winter" in their name, caution would be prudent.
As a Betrayal Trope, expect spoilers.
- Die Another Day: Miranda Frost betrays James Bond and MI6 after Graves bought her out with an Olympic gold medal.
- The Negotiator: Commander Grant Frost is the one orchestrating the whole scheme that stole money from the orphan fund, murdered Danny Roman's partner Nathan Roenick when he found out, and framed Roman for it.
- Salt: The Big Bad of the film (at least as far as we are shown) and the final sleeper agent Salt encounters is known as Secret Service Agent Ted Winter.
- In The Graveyard Book, the Big Bad The Man Jack takes on the name "Jay Frost" when he's trying to exploit the main character.
- Zigzagged in A Song of Ice and Fire, where Jon Snow is sent far beyond the Wall to infiltrate the Wildlings while Reek manages to ingratiate himself into Theon Greyjoy's occupation of Winterfell before revealing himself as Ramsay Snow, the bastard son of the Starks' nominal ally Roose Bolton.
- Max Payne 2: Detective Valerie Winterson, Max's colleague at his NYPD precinct, is in league with the Big Bad Friend Vladimir Lem and attempts to kill Max at the end of the second act.
- Subverted in Second Sight, where WinterICE are the good guys and end up used as scapegoats by the villain in the Bad Future.
- Inverted in Digital Devil Saga 2, where Heat betrays the party.