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This is Fresh Air. I'm David Bienkule. Today we feature our interview with the writer John Green.

He has a huge following, mostly among teenagers who are fans of his young adult novels.

His best-selling 2017 novel, Turtles All the Way Down, has been adapted into a new film.

It premieres on the streaming service Max next week.

Green's previous young adult novel, The Fault in Our Stars, sold over 23 million copies, was on the best-seller

list for 24 weeks, and also was adapted into a film.

His young adult novels wrestle with the kind of issues you'd expect from someone like Green,

who had considered joining the seminary and worked at a children's hospital as a student chaplain.

The Fault in Our Stars is about two teenagers with cancer who fall in love.

Turtles all the way down is about a 16 year old named Aiza who's still getting over the death of her father.

She's also dealing with OCD, obsessive compulsive disorder, which leads to intrusive

thoughts that get in the way of her day-to-day life.

Her thoughts also interfere with her relationship with her best friend

and with her ability to have a boyfriend.

Her obsession is with all the microorganisms that live on and in her body, and her fear that

she will become infected with a deadly bacteria.

Here's a clip from the new film in which Kriacchino as Aza's best friend Daisy is trying to convince

Aza, played by Isabella Merced, that it's safe to kiss her boyfriend.

You know what, I bet that if you guys actually kissed you would not be thinking about 80 million

microbes Ooh What if his microbes are better than yours?

...