While the actors of popular television series like "Heroes" are normally tight lipped about upcoming storylines, actor Masi Oka, who plays Hiro Nakamura on the NBC series, talked freely about the return of a certain fan favorite during a press call earlier today with fellow cast member Hayden Panettiere (Claire). "Jayma Mays is just absolutely fantastic," Oka said of the return of Charlie, who had an ill-fated romance with Hiro during the first season of the series. "We just literally finished yesterday shooting that episode and it just brought back memories and the cast was fantastic working with her. Lots of laughter, lots of crying, heartbreaking... everything that I loved about that storyline all jumbled into one. Episode eight [of the new season] is a really heavy Hiro-Charlie storyline but it was an absolute pleasure and an honor to be working with Jayma Mays again."

Coming back for the fourth season, which bows on Monday, September 21, both Panettiere and Oka still admit to finding challenges in their complex roles. "It's a little tough," Panettiere said, "because even though we are playing the same character you really do have the whole writing staff taking us in whichever direction they want to and on this kind of show there's infinite amount of possibilities in where you can go, whether you stay good, whether you turn bad, who you're working with; it's always a surprise." Does it throw her for a loop when the writers decide to take Claire (the cheerleader with regenerative powers) in a new direction? "We know our characters so well now that we can figure out what they would do in these situations and go from there but really you never know what you're going to be playing."

Oka agreed and said that it's exactly the multi-dimensional nature of his character that helps him always be fully invested. "I think that's what keeps it interesting and challenging. There's definitely something to be said about the familiarity that we want to give to the audience with our character portrayals so the writers put us in various situations and... just like we do in life as we grow and the characters grow and evolve; it's always a constant change and surprise."

While the "Heroes" characters sometimes bounce from being good to bad for storyline purposes, how would the actors feel if their character was radically changed on a permanent basis? "Looking at the stuff we do and the character and changes that we've had and all these different places that they've taken our character it would be difficult if we were territorial," Panettiere said. "I'm not saying there aren't storylines that you don't go 'Wait. Hold on. She really wouldn't do that' or that you're not such a fan of or little lines here or there and you go 'I can't figure out how to say that the way that Claire would say it.' I mean, we've gone to the future and back again, we've gone to the past, all over the world, we've become good and bad... and I just think there's nothing but excitement that we all get from that especially being on the show for four years. We want nothing but spontaneity and change. You get excited from that kind of stuff."

Besides the potential new chapter in his romance with Charlie in episode eight, Hiro is also facing some other heavy - and realistic - problems this year. "Hiro is going through a terminal illness and a bucket list," Oka explained, "and I think he's taking life a little bit more seriously and feeling more of the gravitas yet, at the same time, he has to keep hope alive and it's that dual juxtaposition between life and death and the hope and despair that he is trying to balance."

For Panettiere's Claire, college is a new frontier where she'll explore something she's not used to - normalcy. "I'm dealing with a new best friend and roommate and we have a very interesting relationship together but she's really the first person that she's been able to let in on her secret and somebody that's really a confidante and that's a very delicate balance that can easily fall apart. One little misstep and her dad will bring the Haitian in to wipe their memories and then that will be that. She's happy that she's semi-caught up to normal life; that normal life she's been chasing. Where exactly is that going to go? I think there's going to be some manipulation and just some fun stuff."

Is college an avenue that the 20-year-old Panettiere is interested in exploring? "I love to learn but going back into school... I'm so set in this path that I'm on right now and I'm so excited about it and I love doing it so much that I like to focus myself on one thing at a time but I've found that, like most people, there are subjects that are necessary to learn but you don't really want to learn on top of those that you do want to learn." Despite her love for her busy acting career, though, the actress feels that she gets educated every single day she spends on the "Heroes" set. "To take a class or two on subjects that I'm really, really interested in and curious about would be awesome but I spend so much time with the brightest and most talented and well-rounded people. I've had the privilege of having long and very intellectual conversations with people and sometimes I just sit there and just listen. It's like a better version of a class so even though I'm not per se sitting at a desk and in school I'm still learning all the time."

Evident by their playful bantering during the call, it's easy to realize that Panettiere is joking when she says of the cast, "We hate each other. We don't get along at all." Giving a more serious answer, Oka stepped in and expressed, "We're a big family and we just really love working with each other." How does the cast respond to the critical drudging the show gets from time to time? "When we ride those waves of up and down and everything is good [or] everything is teetering a little bit," Panettiere said, "you feel it and you need to try to be there for each other and make it the best you can which I think we are doing."

While Oka acknowledges that the first season was "lightning in the bottle," he feels strongly about the show being back on track during this new season. "We're making so many bold choices and a lot of creative freedom and I'm really, really excited about this season. I would probably say this is as a favorite of a season as season one if not my second favorite season so far."

Asked why audiences are faithful to the show despite some not-so-favorite storylines over the years and Panettiere explained, "I think because just like we get excited to read our scripts and see what we get to do next, [the audience] gets excited to see what adventure we're going to go on next. There's always these little twists and turns that are exciting. It's just a really fun show to watch." So fun, in fact, that she admitted to recently becoming a diehard fan of the show herself. "I found myself TiVo-ing it because I was working so much last season. I TiVoed all the episodes and come back to watch them back to back to back and I found myself... I could not put my remote down! 'Just one more episode, please!' And this is a show that I'm on and I don't generally like to watch myself but it's exciting and it's smart and I don't think it belittles the audience. It's just one of those rad shows." Then, adding a laugh, she asked Oka, "Did I really just say 'rad show?'"

While Oka and Panettiere have both branched out into film work over the last few years, how does it feel when they return to the set of "Heroes" after a busy hiatus? "It does make me excited to go back to 'Heroes' when I do movies,' said Panettiere, who most recently starred in the film "I Love You, Beth Cooper." "I find so much joy in being able to travel around and play new characters but there is also something settling about coming back to an actual place where you know you're going to go every morning, you know who's there and who's waiting for you and you've known them for such a long time and spent so much time with them. So it's like going home."

The fourth season of "Heroes" kicks off on Monday, September 21 with a special two-hour premiere at 8:00/7:00c on NBC.