Ask many writers where their characters originate and they’ll shrug and say they came from within their imagination; they appear or develop over time.

For me, they’re often sparked by spotting someone in a coffee shop or on a train. I won’t take the ‘whole’ person, but rather ‘pieces’ of them – the way they walk, the way they’re dressed, or something they say – and blend them into a character. 

There’s something delicious about creating someone new in a novel and I love the feeling of anticipation as I plot out who that character is – and give them a name and a back story. By then, I’ll have worked out how and why they’re in the story.

But then … along comes Stella Lastings, a plumply pretty university lecturer, who features in A Falling Friend, the debut novel I wrote with Sue Featherstone. She was originally quite a nasty character who was going to come to a bad end.

And here I hang my head in shame: I based her on someone I know – fatal, as so many readers assume we writers do this. In Stella’s case, I confess I was setting out for revenge. The person she’s based on is someone I once worked with – and she was one of those casual gossips who liked to spread mean-spirited rumours about her colleagues for the sheer delight of seeing how fast they spread round the office.

The character, Stella, based at the fictional University of Central Yorkshire, was supposed to take a dislike to one of the two central characters – Teri Meyer – and bully her. But Teri is not a girl to be bullied.

But then … as I wrote more of Stella and her character developed, I realised there was a reason why she behaved so badly and reckoned that she was a sad and lonely person who found a sense of belonging through making her co-workers laugh at the expense of weaker colleagues. (Plot alert: one of the rumours she spreads about Lee Harper, the other central character, is actually true…) And realising that – and also that my own former workmate was probably a similarly troubled person – I became more forgiving and warmed to Stella, writing her as a much more sympathetic woman.

She appears fleetingly in the sequel to A Falling Friend – to be published August 2017 –but I have great plans for her to take a bigger role in the third book of the Friend trilogy.

Knowing how characters develop as I write deeper into the story, though, I’m not sure how things will end for her.

Read an extract featuring Stella in A Falling Friend in our Read an Extract section.