U-Pick: Character Most Likely to Double-Cross You?

Here's how this feature works: each week I'll post a categorical superlative (e.g. "most sadistic villain" "crankiest father figure" "protagonist you would most like to slap some sense into" etc.) and list a few choices of characters from YA books in a poll. You get to pick! The poll will run for a week, and then in the following post I'll update with the name of the winning character. 

The last U-Pick poll was for the YA Character Most In Love With Him/Herself, and the winner by a hefty margin was...

...Professor Lockhart from Harry Potter!

I'm sure he'll be bragging about the title for a long time to come. This time around, the question is: which YA character do you think would be most likely to double-cross you?

There are lots of choices here, so vote below! (If the book is part of a series, I've just listed the series name. You can decide which book you want to base your vote on.) There's also an option for a write-in vote if your pick isn't listed. If that's the case, please choose "other" and then leave the character's name and book title in the comments :)

EDIT: the Blogger poll did not seem to be working properly (the votes kept disappearing!) so I've created a new poll that will hopefully work better. So if you voted once already with the original Blogger poll, vote again in this new one so your vote can be counted! 

YA Character Most Likely to Double-Cross You?
	Kat (Heist Society; Ally Carter)
	Puck (The Iron Fey; Julie Kagawa)
	Reth (Paranormalcy; Kiersten White)
	Shay (Uglies; Scott Westerfeld)
	Selia (Books of Bayern; Shannon Hale)
	Gen (The Queen's Thief; Megan Whalen Turner)
	Cecily (The Chemical Garden; Lauren DeStefano)
	Adrienne/Widdershins (Widdershins Adventures; Ari Marmell)
	Other (please explain in the comments)
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