20 Horror Movie Characters Everyone Underestimated

In 2015's Intruders, protagonist Anna (Beth Riesgraf) is put at a huge disadvantage considering that she's agoraphobic, and so when three men break into her home searching for money, she's physically unable to make herself leave the house.

But the assailants are surprised to find Anna highly capable of putting up a fight, in large part because her house is fully equipped to deal with a home invasion. 

In addition to a surveillance system, Anna's home has various hidden features - such as a basement with a retractable staircase - allowing her to surprise and trap her attackers.

And at film's end we learn the real truth, that Anna and her recently deceased brother are actually vigilante serial killers who target only child molesters - a response to themselves being abused by their own father, who Anna's brother killed.

Ultimately Anna kills all three men, survives the night, and even manages to leave her house for the first time in a decade - moments before burning it down. 

A far more positive outcome than anyone could've expected at the outset, honestly.