Written from the heart

Debut novelist Tanya Byrne tells us about the story behind her gripping young adult novel, Heart Shaped Bruise

The first thing people ask me when they find out I'm a writer is where I get my ideas. 'Down the back of the sofa,' I usually joke because I don't know what else to say.

I get ideas everywhere - lyrics, graffiti, half-heard conversations on the bus. There's rarely a light bulb moment, usually a series of sparks. So I didn't set out to write a book about mental health. I had an idea about a girl called Emily who loses everything when her father is sent to prison so wreaks revenge on the girl whose testimony sends him there and it unravelled from there.

As I was writing, I kept asking myself if revenge was motivation enough, if most teenage girls would do something like that. The answer was no. But that didn't mean the idea was broken, just that Emily doesn't react like most teenage girls because she isn't like most teenage girls.

I considered several diagnoses for Emily. Was she a psychopath? A sociopath? I eventually realised she had borderline personality disorder.

The causes of BPD are unclear, but it's thought to develop through a difficult life event like the early loss of a parent, in Emily's case her mother leaving when she's three. She doesn't know why her mother leaves, so she grows up feeling insecure, no doubt terrified that her father will abandon her too.

But Emily doesn't know she has BPD. It isn't usually diagnosed until adulthood and the symptoms tend to become worse during a stressful experience, like when Emily's father is sent to prison. Her psychiatrist mentions BPD briefly, but Emily is in denial about so many things - that what she did was wrong, that she should be sorry - that she doesn't dwell on it.

The story is told in a series of journal entries so she doesn't have to; we're only told what Emily wants us to know. So if she wasn't going to tell you that she might have BPD, I had to show you. Throughout the book, she smokes too much, doesn't eat enough and has fierce mood swings, but it's more than teenage angst. Yes, she's misunderstood, like most teenagers, but she vacillates between being happy one moment to crying the next and she has wild bursts of anger that send her flying across the room. She kicks things, breaks things, sets them on fire.

She also takes risks without thinking about the consequences. When she finds Juliet, the girl whose testimony sends her father to prison, it's not just for revenge; Emily is terrified of being alone and fixates on Juliet, then on Juliet's boyfriend, Sid, because she's convinced that if Sid loved her, she'll be fixed. She wouldn't be, of course, and that's what she comes to realise at the end of Heart-Shaped Bruise, the thing we all come to realise at some point, whether we're seventeen or seventy, that when it's said and done we have to fix ourselves.