20 Horror Movies That Made You Root For The Wrong Person

Triangle opens with single mother Jess readying her autistic son, Tommy, for a yacht trip with her friends. However, when Tommy can't attend - supposedly he's at school - Jess goes on the trip anyway. 

When that yacht capsizes, Jess's group seeks shelter on an ocean liner, though things go from bad to WTF when Jess realises that the liner is empty and they're being hunted by a psychopath wearing a burlap sack. To top it all off, they're also stuck in a timeloop.

Now, Jess seems like a sympathetic figure - a single mother exhausted by the demands of her son - though, by the time she arrives on the yacht, she's noticeably disoriented and in need of escape. However, nothing is as it seems. 

After Jess slays the burlap maniac, the timeloop resets. So, believing she can only escape by murdering the others, Jess puts on the burlap mask herself, proving that she was the killer in the original timeline.

When Jess finally makes it home, she realises she's returned shortly before she left for the trip. Looking through the window of her home, she sees Past Jess abusing Tommy. Wanting to be a better mother, Jess slaughters Past Jess and replaces her, but when Tommy dies moments later in a car accident, Jess believes she has nothing to live for and heads towards the yacht port, kicking off the original timeline.

Not only is it a gob-smacking twist, it proves Jess was literally not who we thought.