Kevin McKidd (Rome) said he signed on to Percy Jackson and the Olympians: The Lightning Thief, in which he plays the Greek god Poseidon, for his kids—and he adds that his young son is checking on whether dad will appear in any sequels based on the series of children's books.

"My son, since I started doing it, he's read the first three books," McKidd said in a group interview over the weekend in Pasadena, Calif., where he was promoting ABC's Grey's Anatomy at the Television Critics Association summer press tour. "I'm watching him read the book, and I'm like, 'So, Joseph, am I in this one much?' He's like, 'Nah, nah, you're not. Maybe in the next one, but in this one not so much.'"

In the movie, based on Rick Riordan novels, young Percy Jackson discovers he is a descendant of the Greek gods and goes on mythological adventures in modern-day settings. McKidd added that he is signed for four of the anticipated five films in the series, as much as they feature Poseidon.

"I'm 40 feet tall for most of the film, but then we come to human form," McKidd continued. "We can atomize ourselves because we're gods. We can do what we want, right? So we can atomize ourselves and walk around the streets of Manhattan, wandering Manhattan, and dress in Gap clothing and do all that stuff, then atomize ourselves back to 40-foot Greek god stage. It's a really fun film."

Effects work is still underway, so there has not been a cut to screen for actors yet, but McKidd has heard early reports. "I know [director] Chris Columbus saw a cut," McKidd said. "He saw an early cut of it without the effects laid on yet. There's a lot of effects in it, and he's very excited about it. I think it's going to be really cool. My kids are really excited about Percy Jackson."

Percy Jackson and the Olympians: The Lightning Thief opens Feb. 12, 2010.