[WARNING: The following contains spoilers from Doctor Who's episode on Saturday. Read at your own risk!]

Here's the thing about Doctor Who lately — fans, including myself, can't help but love and hate the series. And goddammit, if you're going to put Game of Thrones' deadly, cherub-faced star Maisie Williams in an episode, don't effing waste her.

Saturday's episode, "The Girl Who Died," was an exercise in frustration on many levels, but it came through in the end. Seriously, we've never identified with a put-upon companion more, waiting for The Doctor (or in our world, executive producer Steven Moffat) to finally make a breakthrough and reveal the big plan already. Williams was a very sweet part of this episode, but it wasn't until the final, dialogue-free moments did we get to see what she could truly unleash. But more on that later.

A Quick Recap

The Doctor (Peter Capaldi) and Clara (Jenna Coleman) get captured by a Viking village through stupidity and kismet. Then, warrior aliens known as the confusingly named Mayans (is there a different spelling?) harvest the best Viking fighters in order to literally ingest their adrenaline and testosterone (which glows neon green) to increase their warlike powers and other quasi-scientific-superstitious stuff. Upset, Viking lass Ashildr (Williams) throws down the gauntlet with the Mayans, which forces the Doctor to conceive of a crazy way to save the remaining villagers that involves electric eels and a psychic storyteller helmet that Ashildr must wear. When Ashildr dies from exhaustion, the Doctor is sad but then rallies and brings her back to life — eternal life — using Mayan technology.

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Immortality

The Doctor, with all of his regenerations, has been painted as a tragic figure, partially because he is destined to be lonely, surrounded by people who keep dying. Damn mortals. With Ashildr joining the ranks of immortals, this adds another intriguing person to the mix who can not only identify with the Doctor's psychological messiness, but also potentially come back in any time period or costume. We fully support this. Already, we've seen from trailers and "Next On" footage that Ashildr will be playing some sort of Victorian- or Regency-era highwayman complete with mask.

What we especially loved about Ashildr's gift/predicament of immortality was the gorgeous, time-lapse shot of her growing into her own. Like Kirsten Dunst's kiddie vamp in Interview with a Vampire, Ashildr is destined to look young (but at least not completely childish) no matter how many years she lives, no matter what tragedies she endures. But we do get to see the change in her eyes and expression through the ages. First we see unbridled, youthful joy, which transmutes into sadness when she realizes the full impact of losing loved ones, and then eventually becomes an almost wicked look as she bitterly accepts her situation. All this Williams expresses with no words, but with just colorful landscapes swirling around her.

And for this we wish there was a spin-off for Ashildr through the ages. It just took a fluffy, inconsistent and illogical episode to get to it.

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Mortality

Clearly, Ashildr dying and then becoming immortal explains the two-part episodes titled, "The Girl Who Died" and next week's "The Woman Who Lived." But really, when can a theme only apply once on Doctor Who?

When the Doctor says that a premonition is just remembering "in the wrong direction" when he sees Ashildr for the first time, could we not say this about Clara, the Impossible Girl? We already know that Coleman is exiting the series, but the episode hammers the idea home that yes, the Doctor is very, very worried about losing her. Is this heavy-handed foreshadowing or a misguided attempt to soften the blow when it eventually happens?

Ashildr

Now that we know Ashildr is immortal but not impervious to harm, we really hope that she won't be killed off. First of all, this would keep the door open to more Williams visits. Also, we really do want to see her in every era possible. What was she like in the Middle Ages? Will she ever go into space again? Would she possibly have a super-meta moment and exist during the height of Game of Thrones mania? Make it happen, Moffat.

Regardless, we're thrilled with the highwayman plot that's already coming: cheeky Ashildr in a mask, giving lip to the Doctor. We. Can't. Wait.

What did you think of the episode and how Williams' character played out?

Doctor Who airs Saturdays at 9/8c on BBC America.