Warning: MASSIVE Doctor Strange spoilers ahead. Don't read any further if you have not seen the Sorcerer Supreme's first solo adventure!
If you have already seen Scott Derrickson's Doctor Strange, then you already know that Mads Mikkelsen's Kaecilius is as ruthless as they come. That said, the actor seems to think that the villain's willingness to kill comes from a place of pain and vulnerability. In a recent interview, Mikkelsen opened up regarding the decision to kill The Ancient One (Tilda Swinton), and explained that it stemmed more from his sense of emotional devastation and betrayal than pure evil. Mikkelsen said:
It was super nice. Obviously, I knew what was going to happen my character, so it was a very nice moment for me as an actor to get the upper hand, you know? He's a legend, she's The Ancient One! But she's not immortal, and I think it's one of these things where there's a lot of emotions about doing that. He doesn't want to kill her because he's evil, she disappointed him so much. He was a broken man when he came to her, and he was getting healed and then all of a sudden, she lets him down so heavily by lying to him, and I think that breaks him completely. So there's a lot of emotions there. It's a love-hate relationship, once he finally, finally gets her.
Upon rewatching Doctor Strange, the rationale provided by Mads Mikkelsen in his interview with IGN makes more sense. When the movie opens, Kaecilius simply seems like a violent psychopath. However, the film eventually peels away the layers of his backstory and provides us with an understanding as to why he's so angry with The Ancient One. Kaecilius is one of the only Marvel villains to actually kill someone important in an MCU movie, and it works because we understand his emotions in the process. He feels lied to, and his turn to the dark side in many ways telegraphs the character arc of Chiwetel Ejiofor's Mordo -- which will receive much more attention and focus in future installments.
I would also like to point out that the death of The Ancient One ultimately leads to one of the most beautiful scenes in the entire Marvel Cinematic Universe. The sequence in the hospital where Stephen Strange (Benedict Cumberbatch) takes on his astral form and speaks to her about the nature of her death is one of the most profound and poignant scenes that we have ever seen from a Marvel movie. It's touching, and it couldn't happen unless the folks at Marvel were willing to let Kaecilius kill her in the first place.
Want to relive these profound scenes over and over again? Doctor Strange will be available on Digital HD on February 14, and the Blu-ray edition of the superhero film will hit shelves on February 28.