(CNN) -- Batman had Robin, Holmes had Watson, Han Solo had Chewbacca; iconic heroes have iconic sidekicks who keep their main man sane and humanized, while providing the audience with a proxy. But whereas the Lone Ranger only had one Tonto, "The Doctor" from 50-year-old British series "Doctor Who" goes through a lot of "Companions" -- so much so that new arrivals are met with fan anticipation and anxiety.
Enter Jenna-Louise Coleman, the 26-year-old actress who officially steps into the role of sci-fi sidekick on the popular BBC America show's Christmas Special. Known to American audiences from the April 2012 ABC miniseries "Titanic," and for a brief role in 2010's "Captain America: The First Avenger," she joins "Doctor Who" as Clara/Oswin, a companion to The Doctor, a mysterious, human-looking "Time Lord."
Played by Matt Smith, he journeys through "Time And Relative Dimension In Space" in his aptly-named ship, the TARDIS -- which looks like a blue British police call box on the outside, and is as iconographic a vehicle as the U.S.S. Enterprise, Millennium Falcon or DeLorean. Launched in 1963, change and evolution is part of the show's DNA. When a lead actor steps down, The Doctor essentially dies and is regenerated into a new body, but as the same character with a new actor portraying him. Smith is the 11th to do so. However, over five decades, more than the 30 companions have been unique characters with their own back-story. The Doctor invites them on adventures across the "time vortex" to face monsters and save worlds. As they retire or die, fresh ones are needed to keep the him company.
Although she is only the latest of companions, Coleman's debut comes during a unique moment during "Doctor Who." Gracing the covers of TV Guide and Entertainment Weekly as a fan favorite, garnering a cover mention in "Rolling Stone" as a best fall show, ranking as iTunes' most downloaded TV show in the U.S., packing the house at San Diego Comic-Con International, Coleman arrives as the global brand has become a bona fide hit in America -- and immediately following the death of popular predecessors Amy Pond and Rory (played by Karen Gillan and Arthur Darvill), Smith's first companions.
Coleman played a surprise role in last September's season premiere -- as Oswin, a different character from Clara, but one connected to her -- and takes on full companion duties in "The Snowmen" Christmas episode, airing December 25 at 9 p.m. ET. A mysterious woman with a secret, Clara is a feisty, flirty foil to a grief-stricken, apathetic Doctor.
"We see him having just lost the Ponds, and he's not in a great place," said Smith. "He's lost his mojo a bit, and his sense of adventure, and I think this season certainly looks at him rediscovering that fire with Clara."
Smith added he is excited for fans to see the developing chemistry between him and Coleman, as well as the "real intrigue" behind the mystery of Clara's identity. And just as the nature of "Doctor Who" is change, Smith said fans will also embrace Coleman's Clara.
For her part, Jenna-Louise Coleman has already embraced her role as a companion. During a recent interview at BBC America's Manhattan offices, she offered insight about her character and her relationship with The Doctor, and weighed in on Clara's soufflé obsession, driving a spaceship, her Bond Girl moment and Christmas traditions.
Can you share a moment when you felt the enormity of stepping into this popular world?
You see "it" everywhere and you're used to it, like I was used to seeing Matt's face all over the place. But, when I was auditioning, being sat on the Tube and you see the posters, and it was always like he was pointing at me . ... (But) there's not very much time to analyze as you go. It is only now that I feel like I've just been playing with all my mates for the last couple of months, and then suddenly, I'm like, "but people are going to see this," you know?
What would you like to add to the legacy of the show as Oswin/Clara?
I like that it's not plain sailing. Like (executive producer Steven Moffat) was saying, it's not very interesting if you come in and it's like this friendship straight away. He's been very clever in creating a mystery, because, no matter what, it's always going to be hard to bring in somebody else into the show, when Matt, Karen and Arthur started out together, and you're used to seeing them on screen together.
How would you define your character's relationship with The Doctor?
I like that she holds her own. You know, The Doctor's this amazing man, and she's like, "You know, cool. I think you're amazing, but so am I." So, it's a nice double act.
Has Karen offered advice on joining the show?
She's been really supportive. ... She came to the screening in New York City with Matt, and when Oswin was on screen, she texted me saying it was great. (But) from interviews I've seen of Karen, she was saying she didn't want to, because she wanted me to have my own experience. I did want to be like, "What do I need to know? Tell me everything!" But she's been really cool about it.
There was never a realized romance between The Doctor and Karen's Amy, but your character gets flirtatious straight away, right?
It's been interesting how it's changed Matt's Doctor. There is a natural bounce between them, and a flirtation, and attraction. But, again, they've always got this friction because they're a bit magnetic and drawn to each other, but she can't quite figure him out. He's got loads of secrets and he's always looking at her, trying to figure her out.
Can you tell me about the first meeting between you and Matt?
He's with the same agency as me, so my agent said, "You're going to be reading with Matt and he's lovely. He'll take care of you." I walked into the room and he's just like, "Heeeeyyyyy," and gave me a big hug. He really helped me out in the audition. I've read with other actors in auditions before, but Matt really got involved so it was like we were both auditioning together almost.
This is an iconic franchise, but are there other big franchises you'd want to step into?
Totally! I'd love to be a Bond Girl. I did have my Bond Girl moment -- well, what I thought was going to be, but it was very much a "Doctor Who" version. Like being on the back of a motorbike, but then we've got the goggles and the hat, so it was like "Doctor Who's" take on James Bond.
Have you played with any cool sci-fi gadgets on the show, like the TARDIS?
There are certain parts of the TARDIS which I love. We've got these new kind-of rolly balls, which is my favorite. But my character got to drive the TARDIS at one point!
In the long list of "Doctor Who" monsters, what's your favorite?
The Weeping Angels. It's the concept (that they only move when you aren't looking at them). But there's one at the end of this season -- it's a new monster, and I'd say you have to wait and see that. That one is my favorite, so far.
One of the things we know about your character is her love of soufflé. Have you tried making one?
I had to be baking one in a scene recently. So I got the Google up and tried to figure out exactly how to do it, take it kind of really seriously to make sure I've got, like, the whisking right. But maybe that's what I should do over Christmas.
Is it odd returning to a "normal" world after living in The Doctor's?
"This" life is so exciting on a daily basis. Everything's so dramatic every day, and it's the end of the world every week. You're either running or there's a snow machine or rain machine, or you're in a harness and you're on wires. ... On an off day, I find that I get bored quickly, like, "Where's the Cybermen?"
The "Doctor Who Christmas Special" is something of a tradition -- do you have others you'll keep?
There are 13 of my family going to a cottage, so we'll be there watching. It's one of my grandmum's favorite shows, so it's big for her. But normally I get home from London and I haven't seen my family for a little while, and me and my mum always wrap the presents the night before with a glass of Bailey's. That's my favorite tradition at Christmastime.
What did your grandmother say when she learned you got this role?
I auditioned for Amy's best mate in it, and was pretty close to getting the part, and my grandma was absolutely devastated I didn't. So, we came back around, and I don't think she can believe it, actually. It is quite surreal for her, and she's quite looking forward to meeting Matt.
What do you anticipate that encounter being like?
My grandma's going to mess up his hair. She's going to be patting him and hugging him, and Matt's going to have really messy hair for the rest of the night.