Evil Orphan

For the sake of the story, the young couple will have no idea anything is wrong, but tropers will know right away that there's something not right with this newcomer.

The child is a Creepy Child who looks like they strolled out of the Uncanny Valley and it's not long before things start going wrong around them like pets start acting up, things go missing, there are fires, injuries and nocturnal birds of prey show up everywhere.

As if they don't have enough to worry about, the couple's biological child is making up crazy stories about how the orphan is planning to kill them all in their sleep! They will be ignored.

Sometimes one or both of the parents figure it out at the very last minute and Sometimes it falls to the children to stop them.

Feminine pronouns are used because Evil Orphans are like creepy children and little girls, but evil little boys are sometimes used.

The Evil Orphan is the modern-day incarnation of the Changeling Tale. It uses the tried-and-true horror of Subverted Innocence and the Devil in Plain Sight as there is little that can compare to the fear and revulsion of discovering that one has been succoring evil incarnate in one's own home.

It may cause us in horror when the audience wonders just how she became an orphan in the first place. The polar opposite of the Heartwarming Orphan.

Example

 * The Omen (1976): The boy Damien is an orphan substituted for the couple's real child, who died shortly after birth.


 * The antagonist of Thor and The Avengers (2012), Loki had this trope forced on him, seeing as he was lied to his entire life about his parentage. He didn't become evil until he found out that he was adopted.