Dr Kim Chilman-Blair met Wendy during her medical training.
Her young patient was keen to know more about her condition, but there was no child-friendly material to help.
Her colleague, Dr Kate Hersov, had similar experiences and came to realise the need for such information was international.
While working as a house surgeon in Hawkes Bay, Dr Chilman-Blair completed a masters in entrepreneurship at the University of Otago to give her the skills to develop the idea of a multimedia health information system for children with illnesses.
While it was hard work at the time, it gave her the incentive and the discipline to turn the idea into reality and by 2006 she and Dr Hersov had founded Medikidz.
The books, designed for children aged 10-15, feature five superheroes - each specialising in a different part of the human body - and a brain on legs.
Each book is co-written by doctors and graphic novelist John Taddeo (of Marvel Comics fame) and peer-reviewed by leading health professionals in the relevant field.
More than 20 titles were launched last September and in the United Kingdom sales have already topped 600,000 copies, with the books on HIV and leukaemia particularly popular.
Dr Chilman-Blair is now working full-time with the business, which has 20 staff.
She said the hardest thing about the project had been her temporary move to the United Kingdom to build the necessary business relationships.
Books to help children understand conditions which might affect adults around them are also being written, including subjects such as breast cancer, bowel cancer and Alzheimers disease.
Medikidz also offers children with illnesses a social network site where they can share information and offer peer support online.
The books were launched in New Zealand this month.
The Otago Daily Times tested the Wendy book on Dunedin school St Brigid's pupil Isaak Beard (11), whose fellow pupil and cousin, Taylor Hamilton, has epilepsy.
Taylor's mother Chriss Hamilton, president of the Otago branch of the Epilepsy Association, said she knew the book with its slightly irreverent tone must have hit the right note when she heard Isaak laughing out loud.
Epilepsy was not an easy condition to explain because there were a variety of seizures.
They could also change as the child aged.
At this stage, Taylor, who was diagnosed with the condition as a baby, had "absence seizures" where she looked as if she was day-dreaming.
While these might only last for 10 to 30 seconds, they could be dangerous when she was on the road or swimming.
She could see the books being useful to association field officers in the work they did to educate people about the condition.
Isaak, who already knew about the condition because of his involvement with Taylor, said if information was put in a "normal book" some children would not be interested, but " a lot of kids are interested in comics".
