Why Do We Ignore the Red Flags? The Psychology of Toxic Relationships in Psychological Thrillers

One of the things I love about psychological thrillers is that they make us suspicious.

A character says something that doesn't quite add up, or a partner seems just a little too interested in where their loved one has been. And as readers, we notice.

That's a red flag. Something isn't right. Don't trust them. Sometimes we're right, and sometimes we're spectacularly wrong, but that's part of the fun.

Psychological thrillers also tell us something fascinating about ourselves: how difficult it can be to recognise red flags when we're emotionally involved.

From controlling partners and manipulative friends to gaslighting, jealousy, obsession and deception, some of the most compelling thriller plots are built around behaviours that can initially appear completely harmless.

So why do characters — and real people — ignore the warning signs?

Red flag 1: Control disguised as care

One of the most interesting behaviours to explore in psychological thrillers is control.

It rarely begins with: I'm going to control your life. It might begin with:

Text me when you get there.

I worry about you.

I don't trust that friend of yours, or

Why would you want to go there without me?

On their own, these comments might sound caring, which is what makes them interesting.

In a thriller, we might gradually discover that concern has become surveillance, affection has become possessiveness, and protection has become control.

Book example: I Let Her In – You look so much better now you've got changed as I asked. Just how I like you. Jon is a character who initially appears attentive and caring but whose behaviour becomes increasingly controlling.

This is one reason psychological thrillers can be so uncomfortable to read. The behaviour doesn't necessarily begin as something obviously frightening. It evolves and by the time the character and the reader realise what's happening, the situation may have changed completely.

The tropes in In His Shadow

Red flag 2: Making someone question their own reality

Gaslighting is another behaviour that appears frequently in psychological thrillers.

The term has become part of everyday language, but its fictional possibilities are particularly powerful.

Imagine a character who remembers an argument, but their partner insists it never happened. Or they remember seeing something, but they're told they're mistaken.

Eventually, the question isn't simply What happened? It's: Can I trust my own memory? That's a terrifying position for a character to find themselves in, and it's incredibly effective in fiction because the reader has a privileged position. We may know what really happened, but the character doesn't.

An example from another of my books is In His Shadow.

Nicola knows deep down from the off that she shouldn't be marrying Hugh. And almost from the moment the ink is dry on their marriage certificate, he's controlling her emotions. He takes money from her account, telling her that she agreed to it and sends a resignation email to her employer, insisting to her that she sent it herself. And this is just the tip of the iceberg.

Red flag 3: Isolation

Another warning sign that frequently appears in psychological thrillers is isolation. Again, it doesn't necessarily begin dramatically. A character might simply hear: I don't really like your friends. Then: They're not good for you. Then: Why do you always need to see them?

Eventually, relationships outside the central one begin to disappear, and in fiction, this can create a claustrophobic atmosphere because the character has fewer people to turn to, fewer people to question what's happening and fewer opportunities to hear someone else say: That isn't normal.

An example of this is The Married Couple, and in this book the expected gender roles are flipped on their head where it's the wife who's doing everything in her power to isolate her husband from the world.

As readers, we're often screaming at the page at this point. Tell someone! Leave! Don't go back! But again, we have something the character doesn't have: distance.

Red flag 4: The charming person everyone trusts

This is one of my favourite psychological thriller devices. What happens when the person we should distrust is the person everyone else adores? They're often charming, helpful, funny, generous, and everyone thinks they're wonderful. Except perhaps one person, and that person starts to look paranoid.

This is particularly effective because our perception of a person is heavily influenced by what everyone else thinks of them. If ten people tell us someone is lovely, we're more likely to believe them. Psychological thrillers love turning that assumption on its head.

In I Don't Like Mondays, there are one or two lovely characters in supporting roles who everyone else likes. Perhaps they shouldn't be trusted? Or perhaps me suggesting this is a red herring in itself??

Thrillers can truly manipulate us. We may be completely convinced that we know who the villain is, and then the author reveals that we've been looking in the wrong direction all along.

Red flag 5: Jealousy disguised as love

Jealousy is another classic thriller ingredient. I'm only jealous because I love you. Or I just don't want anyone taking you away from me. Or why were you talking to them?

The line between affection and possession can become blurred, and that's exactly where psychological thrillers thrive. A character might initially interpret jealousy as evidence that someone cares deeply about them. The reader, however, may begin to see something darker underneath it.

This doesn't only apply to romantic relationships. In my novel, Frenemy, Book 1 of The Dark Heart Series, jealousy is applied to a longstanding friendship. Lou's best friend Donna is not only jealous of Lou's blossoming new relationship, but she's also jealous of her life.

The interesting question isn't simply whether jealousy is a red flag. It's when does jealousy cross the line? That's a much more interesting question for a thriller.

The tropes in Their Last Days of Summer

Red flag 6: The lie that seems too small to matter

Some of the best red flags in psychological thrillers are tiny: A character lies about where they've been, or they hide a message.

The protagonist notices but then dismisses it, because surely such a small lie doesn't matter. Except, of course, the reader knows that in a psychological thriller, small details matter enormously. A tiny inconsistency can become the thread that unravels everything.

You'll see this right at the start of Their Last Days of Summer when Andy lies about a text he receives. You'll know he's lying, but his wife accepts what he's telling her. This acceptance will come back to bite her - big time.

This is one of my favourite things about writing thrillers. You can plant something almost invisibly early in the story and have the reader suddenly realise much later: Oh, that's why that happened.

Why do we ignore red flags?

This is where psychological thrillers become particularly interesting because the question isn't really: Why didn't the character see it? It's: Why might any of us fail to see it? When we're emotionally involved with someone, we're not objective observers - we want to believe people we love, and we explain away behaviour that doesn't fit the version of them we believe we know.

That makes us very useful characters for thriller writers because our desire to believe the best of someone can become exactly what puts us in danger.

The red flags readers spot immediately

One of the joys of discussing psychological thrillers with other readers is discovering which warning signs everyone else spotted. Sometimes I'll read a book and think: How can they not see what's happening? That's the brilliance of the genre. We're all looking for clues, and we're all trying to solve the puzzle. Yet we're all bringing our own experiences, assumptions and expectations to the story. A behaviour that screams danger to one reader might seem completely innocent to another, and that's what makes discussing psychological thrillers so much fun.

What psychological thriller red flag do you always spot?

I'd love to know which behaviours make you suspicious immediately — and which ones authors have successfully used to fool you. Leave a comment below to let me know.

Thanks for reading!

Maria x