OnlyOnAOL: 'Fantastic Beasts' cast reveals what J.K. Rowling is really like

By: Donna Freydkin

Eddie Redmayne and wife Hannah Bagshawe are the parents of infant daughter Iris. Someday, Redmayne will earn major cool-dad points for headlining J.K. Rowling's "Fantastic Beasts and Where to Find Them," playing magical creature wrangler Newt Scamander.

Just not quite yet, says his costar Katherine Waterston, who plays the grounded, practical witch Tina.

"All of her friends, when she's ten, will be like, 'Your dad is in the "Fantastic Beasts" movie and she's going to be like, 'That's so lame.' She'll be the only kid in the class who won't care," says Waterston. "You don't realize your parents are cool until you're in your 20s."

Be that as it may, entering the world of Harry Potter was magical for Redmayne.

"The work itself was wonderful and the experience was wonderful. I hope (there will be a sequel). It's a wonderful feeling – it doesn't always happen," says Redmayne, who won an Oscar for playing Stephen Hawking in "The Theory of Everything."

See more: OnlyOnAOL: 'Fantastic Beasts' stars Redmayne, Waterston on creating their own wands

The film mark's Rowling's screenwriting debut, but she gave the cast plenty of room to do their own thing.

"She allowed us all the freedom to play with David (Yates, the director). She didn't come to set too often because she didn't want to distract us," says Redmayne.

For major Potter fan Ezra Miller, the experience of being in the film as mysterious No-Maj (aka human) Credence was, simply, "blissful. It's like when Harry gets into that rich bubble bath in the fourth book. Steamy and delightful. That's what it felt like."

He met Rowling "on one golden day." His costar and fellow No-Maj Dan Fogler, meanwhile, spent more time with her. "She's quite stunning. The energy she emits is palpable. She has this incredible command of this universe. Her energy is incredibly infectious. When she was on set, to pick that incredible mind for any amount of time – we became like kids," he says.

Adds Waterston: "There's an energy on set that's warm and positive. Meeting her is wanting to see her every day. She's so self-effacing."

So is this cast -- who end the interview with Waterston sitting in Miller's lap, cuddling with him after a long night spent premiering the film.

"We're all in it together. That's the message of the movie," says Alison Sudol, who plays bubbly Waterston's sister, the witch Queenie.