The season nine finale of Doctor Who airs this Saturday and its been another fun, scary, emotional, and loopy season. But one thing season nine has confirmed beyond doubt is the masterful embodiment of the twelfth Doctor by Peter Capaldi. He started out strong and confident in his characterization and has perfected the role over the past two seasons with subtly and grace. None of his tweaks seem unmotivated or out of character, coming with the mellowing of time, comfort, discovery, and solid character development. As the season closes and the long two week wait for the Christmas Special begins, we can take a look back at the season and relive the Peter Capaldi defining moments as the Doctor.

6. When he rode into an actual ax battle on a tank playing an electric guitar.

It was the season opener and the star of the Peter Capaldi second season as Doctor. He was in some kind of trouble so he decided to have some fun in the middle ages by bonding with a load of vikings and introducing them to the word “dude” hundreds of years early. They loved him, and he had the time of his life. Its hard to explain why the entrance was so perfect  – something to do with the multiple anachronisms and the complete epicness of bringing a tank to an ax battle, or maybe it was the sonic sunglasses – but it just kind of summed up what kind of Doctor Peter Capaldi is, and he’s all kinds of rock n’ roll.

5. “I’m not a hugger.”

One of the few complaints logged against the Peter Capaldi Doctor last season was his unapprochability, his alienness, and his sterile manner. I loved how alien he was, how anti-sentiment and completely socially inept. Season two has seen a softening of those rough edges while preserving all the best bits of the character. He’s still adorably socially inept and very alien, but he enjoys himself more, lets his hair go crazy, wears a hoodie, plays an electric guitar, wears sonic sunglasses, and occasionally shows some affection. One of my favorite moments was coming to find that Clara was still alive after her life had been threatened. He runs joyously towards her, stops himself short, claims he’s not a hugger, but then goes in for a big hug anyway.

4. He’s ancient and forever.

While he may have saved a viking village and turned the girl who helped him immortal, he comes to discover a painful truth about humans when they are cursed with eternal life. Ashildr’s (Maisie Williams) human brain isn’t large enough to house all the memories from her life, and so looses the emotional connection to memories and life in general. In effect, she has lost her humanity and the capacity to care for it – a problem the ancient Doctor has also struggled with throughout his long life. That, in effect, is the reason he travels with humans – to be reminded of his own humanity and the many joys life can still bring.

3. How the Doctor is against war but discovers that he’s also part of the problem.

In the excellent two part Zygon invasion episode, we learn that Zygons have been living in peace amongst humans, disguised in human form. There is a failsafe put in place, called the Osgood box, and watched over by the two Osgoods – one human, one Zygon. Of course, Missy kills one Osgood, throwing the other into despair and grief. An extremist cell breaks out among the Zygons, threatening to end the hard won and precarious peace between human and Zygon. The Osgood box is a masterful failsafe, worthy of the Doctor’s manipulative and complex mind, and he gives a painfully impassioned speech which tells about his own dark experiences in warfare. He wins in the end, but for some reason the Doctor finds himself obsessed with whether the surviving Osgood is human or Zygon. She keeps telling him it shouldn’t matter, and that he won’t know until it doesn’t matter. Even with all the Doctor’s wisdom and peacekeeping, he finds himself guilty of the prejudices that turn us to war.

2. The pain of an unsolved mystery.

There have been some creepy weird episodes this season, but perhaps none as creepy weird as Sleep No More in which the sleep dust in your eyes eventually resolves itself into a monster if you stop sleeping…or something. Its all sort of found footage, completely with a warning not to watch it. Of course you do watch it, and as the story unfolds the pieces don’t quite seem to come together. The Doctor knows it too, and as the ship is collapsing around him and death is imminent, he’s still compelled to stay and solve the mystery. Clara drags him away to the safety of the TARDIS, but he nearly dies struck motionless by the mental challenge.

1.His unrelenting determination.

We know the Doctor never gives up, but never like in Steven Moffat’s masterful Heaven Sent. There’s a lot I love about Moffat and a lot I really don’t like. In general, I think he’s best for Doctor Who in a purely artistic and contributory capacity and not as a showrunner. I personally think the show’s been a bit of a mess since he took over. However, Heaven Sent has been the best episode in a really long time, and arguably the best in Moffat’s reign as producer, and not least of all because of the phenomenal performance by Peter Capaldi as the imprisoned Doctor. Trapped in an unusual prison and pursued by a monster from his nightmares, the Doctor spends his time running and thinking and exploring and surviving. The thing that really bothers him is that the stars don’t see right. As tired as the Doctor becomes, that’s nothing compared to the true scope of his struggle. But one thing is constant. The Doctor wins.