Woman records 82-year-old grandma's reaction to reading 'Fourth Wing'

Author Rebecca Yarros' fantasy novel "Fourth Wing" has quickly become a runaway hit since it was published last April -- especially on #BookTok.

Among Yarros' many fans is one unlikely reader, an 82-year-old grandmother in Australia named Glenda, who didn't want to share her last name for privacy reasons.

Tegan Martin told "Good Morning America" it was her idea to give her grandma Glenda a copy of "Fourth Wing" on a family trip after learning her grandmother had forgotten to pack a book.

"I thought it would be so different from what she normally would read," Martin said. "I was like, '[There are] dragons, and what would she think about that?'"

Plus, Martin said she thought it would be "hilarious" too since along with dragons and its fantastical elements, "Fourth Wing" is also well known for its romance, unlike the historical sagas and novels toward which Glenda typically gravitates.

"I just wanted to know what she thought. What's wrong with wanting to add a little bit of spice to her life?" Martin continued.

Martin has been sharing her grandmother's reactions to the book in an Instagram video series, even drawing the attention of Yarros herself.

"To her credit, [my grandmother] did read it, and her immediate reaction to it was just so hilarious, unfiltered and honest," Martin said. "Seeing her reactions just brought me so much joy, and it was just innocent and funny, and I wanted to share that with other people, because I thought, 'I reckon people would love that.'"

"Also, you see reviews about books from lots of different people, but none of them are grandma's age. So what would a grandma think of a book like this? I wanted to share that with people," she added.

Glenda said at first, she wasn't so sure about "Fourth Wing," but she stuck it out and many parts turned out to be quite interesting.

"It was so different, and I said to Teagan, 'The spicy bits were so spicy -- Teagan, I'm gonna have to stop reading this at night when I go to bed,'" Glenda recalled jokingly.

Both grandmother and granddaughter said their shared experience has brought them closer.

"It's bonded me with Grandma on another level, because I was already pretty close with Grandma, but this is just something new and something totally different that we now share," Martin said, adding that it has simply been "a lot of fun."

Glenda, a grandmother of nine, said that since finishing "Fourth Wing," she has begun reading its sequel, "Iron Flame", and is open to the idea of reading more fantasies.

"Teagan introduced me to something that I would never have chosen to do on my own," Glenda said. "When we get older, I think it's really nice to share with younger family members or whoever and do it because you can get a lot out of it -- not only about the book, but about each other."

"I think it keeps me young," she added.