Amiah Miller plays Emma, an angry, anti-social and unusually quiet girl who despises her parents (Scott and Karen) as well as her nanny (Gwen) and wants to go live in the water with her allegedly imaginary friend the Fish Man.
House by the Lake contains examples of:
- A House Divided: Scott, Karen and Gwen all start fighting amongst themselves once Emma disappears. Even after they do find her, Scott and Karen go back to arguing since Karen is still traumatized by the events.
- The Bad Guy Wins: Fish Man kills Gwen, takes away Emma from her parents and disappears into the sea with her.
- Big Bad: The Fish Man.
- Cell Phones Are Useless: After Fish Man lacerates Gwen's neck, Scott in a panic calls for an ambulance. His call fails to correspond with an operator, and Gwen is left to die.
- Creepy Child: Emma.
- Downer Ending: Emma successfully escapes with the Fish Man into the water and presumably will live underwater with him for the rest of her life away from her parents. Gwen got killed by Fish Man, and the film ends with Scott and Karen driving away from the house grieving over the loss of their daughter accepting that she's gone and they cannot search for her any deeper in the water or they'll drown.
- Emotionless Girl / Ice Queen: Emma. The most ardent evidence that she is this is when she watches and let (with a blank expression) Gwen get her neck bitten off by the Fish Man in cold blood and proceeds to watch Gwen die from blood loss.
- Enfant Terrible: Emma. Yet everybody loves her because she's adorable.
- Everyone Hates Math: Emma when Gwen tries teaching her algebraic expressions. Not that Emma finds it hard, she just finds it so dull she refuses to do it.
- Jerkass: Gwen, the nanny. All she cares about is sounding smart and arrogantly trying to be regarded as a genius, having no interest in Emma's constantly bad mood only wanting to cram algebra down her mind (only making Emma get angrier). When Emma goes missing, Gwen's first reaction is not to find where Emma is but rather show off her work in deducing why she disappeared to Scott and Karen. In the end, she gets slashed by Fish Man before she can take Emma away from her own parents and bleeds to death.
- Missing Child: Emma becomes increasingly harder to find for her parents and Gwen as she keeps mysteriously disappearing. Emma then admits she was practicing breathing underwater so that she can go live with the Fish Man who is lonely without her. The longest period of time she went missing (which is when the cops were called to help find her) would indicate that she perfected breathing underwater and that she was in the indoor jacuzzi the whole time they were searching.
- Parental Neglect: Scott neglects looking after Emma in favor of playing catch with half-naked Gwen who goes shirtless. He incurs his wife's wrath for doing so.
- Police Are Useless: When Emma goes missing, her parents call in the cops to track her down. The cops have no success and only look around territories that Emma couldn't have gone into. Gwen does find Emma, and although the cops did nothing, Scott gracefully thanks them.
- The Runaway: Emma at the end.
- Sanity Slippage: Karen as a result of Emma being hostile towards her.
- Screw This, I'm Outta Here: Emma clearly doesn't want to be with her parents (she hates them), and then we learn she wants to go live in the sea with the Fish Man.
- Slashed Throat: How Gwen dies.
- Skewed Priorities: Once Emma goes missing, Gwen keeps trying to tell Scott and Karen about the Fish Man in Emma's drawings. Scott and Karen care more about where Emma is, not why she's missing. Because Gwen can't tell where Emma is just from her drawings of the Fish Man, she cares more about trying to sound and come off as a genius for knowing what's made Emma disappear instead of helping Scott and Karen find their daughter.
- You Are Too Late: Scott and Karen as they witness Fish Man and Emma walking away into the ocean run after her, but arrive about half a minute too late. They would gotten there sooner if they had not spent time trying to save a dying Gwen but then they didn't bring any weapons and Fish Man could have gutted them just like with Gwen if they did arrive in time.
