If, as Franklin D Roosevelt put it, we have nothing to fear but fear itself, Susie's got it made. Fear does not appear in her vocabulary. She has never been fazed by heights, by the bogeyman, spiders or snakes, by failure (or success), by crowds, by being alone, by being told off or caught out.
To all around her, she's as happy and brave a 15-year-old as they come. She bounces into school every day, slightly shambolic - because she's not afraid of the ridicule of the Style Police - and full of the joie de vivre that comes with believing she can tackle anything. And indeed, she can do most things.
Academically, she loves analysing and working out things for herself. She is blessed with the kind of free-ranging mind that enables her to take great leaps of thought and imagination, making connections that others avoid making for fear of being wrong.
And she's popular because of her charismatic personality. When the world's your oyster, you want to populate it with people who like doing things you like to do. And although many of her friends prefer a quieter life, when they're with Susie they feel obliged to set aside their trepidations and follow her lead.
Take the time, for instance, when she decided that it wasn't necessary to wait two years to get her L plates and take driving lessons.
She "borrowed" her mother's car keys, made copies and put them back before her mum suspected anything. Then, when her parents went away that weekend, she managed to outwit her auntie who was looking after her and drove her friends all over town. "You're incredible," said her two chief admirers. "I know," laughed Susie as she slightly grazed a parked car's bumper.
But while she appears unassailable to her peers and, it must be said, to some of her teachers, there are some important things that Susie hasn't mastered terribly well. The key one is recognising that fear is sometimes not only appropriate, but necessary for survival. For instance, she is so unafraid of failing at school that she puts in a fraction of the time that the others do on homework and, as intelligent as she is, it sometimes shows.
Then there are the physical risks that she takes. Impervious to dangers that are apparent to everyone else, she doesn't think twice before launching herself into a boys' football game or diving into a crowded pool without looking.
That she has only ever suffered a chipped front tooth and a broken ankle - the latter sustained after a parachute jump arranged by her parents for her 13th birthday - is something of a miracle.
But Mum and Dad spend sleepless nights wondering what will happen when she becomes aware of other temptations. Will she try heroin in the certainty that it can do her no harm? Will she engage in unprotected sex under the same illusion? Will she hitch-hike and make forays into dodgy "but really interesting" places because she believes herself inviolable?
While all adolescents take some risks, the Susies of this world don't know when to stop.