The books in the Handbook for superheroes series created by the married author and illustrator couple Agnes and Elias Våhlund.

Elias Våhlund is the author of the books and Agnes Våhlund is the illustrator. Elias is responsible for all the writing, but the stories are developed between them as they both come up with ideas and Agnes visualizes the events through her pictures.

Elias Våhlund

Elias Våhlund was born in 1973 and grew up in Arvika in Värmland, Sweden. Nowadays he lives on Lidingö together with his wife Agnes Våhlund. Before he came to write children's books full time, Elias has been a circus artist, a career that began through a physical theater education followed by circus school in France and performances around Europe, and a university degree in circus from London. Elias is also a trained chef! The philosophy that "you can do and achieve what you want if you are ready to work for it" that permeates the Handbook for Superheroes and Lisa's personal journey is both something that can be seen in his own career, and something he mentions in an interview with Barnens Bibliotek in April 2018, where he takes up Ingemar Stenmark's quote that "the more I train, the luckier I am".
Link to an interview with Elias Våhlund

According to Elias Våhlund, the most fun thing about writing is to spend time in his fantasy world, as if he is playing with dolls in a dollhouse. The most difficult thing is that all ideas and stories have to go so many rounds, be redone and edited over and over again before everything fits and is connected. It is important to have the energy to see when something needs to be edited and rewritten and what.

Agnes Våhlund

Agnes Våhlund was born in 1985 in Warsaw, Poland. Agnes has been drawing for as long as she can remember. As a child, all she had to do was give her papers and crayons, and she kept herself busy and entertained all day drawing and doing things. When Agnes got a little older and found comic books, this was something that inspired her art style a lot, and laid the foundation for how her pictures look today. All images in the Handbook for Superheroes are drawn digitally, using Photoshop and a Wacom Cintiq. Agnes started drawing digitally already as a 13-year-old, and before she started working full time with Handbok för Superhjältar mainly worked as a graphic designer and photo editor.

A funny trivia about the pictures in the book series that Agnes mentions in an interview with Barnens Bibliotek from May 2020 is that while Rosenhill where the books take place has no definite place in the real world, the buildings are collected from slightly different places that Elias and Agnes have traveled to. When they have seen a building that they think fits into Rosenhill, either Agnes draws it, or they take a picture. So, in the books you can find buildings from Notting Hill in London, Krakow in Poland and Vimmerby in Småland.
Link to an interview with Agnes Våhlund