Mary's (Adelaide Kane) reign as Queen of Scots has finally come to an end, and even though we all knew it was coming -- come on, you totally hit up her Wikapedia page to find out whether she lived happily ever after or got her head chopped off -- it was still a brutal finale.

After getting her son back safe and sound, Mary made the understandable but ultimately disastrous choice to have her husband killed. The plot led right back to her, forcing her to leave her infant son in the care of her brother after being arrested.

Flash-forward 21 years later, and we get to see Mary's final moments before her execution (for a plot to kill Elizabeth that we didn't hear much about). Luckily, we were spared the gruesome details of her death and instead got to witness her well-deserved happily-ever-after.

In heaven with Francis (Toby Regbo), Mary finally got to rest in peace with her true love.

TVGuide.com spoke with showrunner Laurie McCarthy about constructing this final episode, and whether or not Catherine's (Megan Follows) ambiguous ending could lead to a potential spinoff.

Why did you consider it necessary to include a 21-year time jump to the end of Mary's life?

Laurie McCarthy: We always took liberties with history, but there were certain events we felt bound to; Mary's death being the largest and most important one of them.

The ending montage with Francis was a beautiful way to finish the series. At what point did you know you wanted that reunion to be the end?

McCarthy: When one looks back on Mary's life it seemed so tragic. But there was so much joy in it. Historically she was said to find happiness and friendship even in her years of captivity. I wanted to celebrate where the show began, which is with a love story.

Mary's marriage was a political one and for our Mary, and our Francis, it was an unexpected miracle that they fell for one another. I felt that in her darkest moment that was a place her mind might go. The scene was filmed before Toby Regbo left the series - we shot it and just held it not knowing when the end would come but knowing what it would be. I think I was toying with the idea of Mary's final thoughts being of her life with Francis, of being spiritually reunited with him, as early as Season 2.

Did you ever consider appearances from other original characters like Bash or Kenna?

McCarthy: Yes, absolutely. All the time. But many things complicated the possibility - not only the actors' availabilities, but the amount of characters we had on our existing canvas at any given time, not to mention in three nations (Scotland, England and France). Bash and Kenna are characters I will always love (and I adore Torrance Coombs and Caitlyn Stasey as well).

Adelaide Kane, <em>Reign</em>Adelaide Kane, Reign

Tell us about that Narcisse/Catherine/Emanuelle threesome!

McCarthy: Well, it just seemed time for a witchy-3-way, didn't it? Catherine was already dabbling in the occult and she's so powerful and so sexual... I always loved that she and Narcisse felt so evenly matched. So we just had to get them together one last time. I liked that she owed the witch payment for manipulating her sons (by killing the girl who came between them), and that Catherine's last sexual encounter on the series serviced that debt... she just didn't know she was servicing a larger evil as well.

Can we consider Catherine's ending with her daughter Margot a bit of an open door? Seriously, we all just want this spinoff to happen.

McCarthy: I want it to happen too! So yes. Please consider it an open door. And spread the word, because Megan Follows is amazing, and back at this moment in history France is ripe for some insane story, and Catherine de Medici and her passionate, blood-thirsty and nutty brood were only just getting started...

Which storylines over the course of the last four seasons were personal favorites?

McCarthy: The evolution of Mary and Catherine's relationship was woven into many storylines, but it remains top of my list. There was something so heartbreaking about a girl who never really had a family and a woman whose own children were destined to resent, if not despise, her.

I wanted to start them deeply at odds with one another, which is why the series kicked off with the prophesy that Mary would cause Francis's death. That, in our world, Mary did inadvertently cause his death, and that Catherine would come to love her anyway (and that Mary would be able to forgive Catherine her many transgressions) seemed an impossible hill to climb, which made me all the more determined to achieve it. Their relationship allowed Mary to grow, to harden at times, to lose faith but also to find compassion and understanding for Catherine and from Catherine. Their bond allowed many conversations about power - about what it cost women, in particular, which is to say nearly everything.

Were there any storylines you wish you'd written differently?

McCarthy: Of course. You always second-guess decisions but the show was very much a collaborative adventure. I worked with the smartest, most extraordinary writers, I listened to everything they said - their ideas and their concerns - and they listened to one another, and we did our best. We had such game and gifted actors, and our production was fearless too. No challenge was too big for them to try and tackle. I couldn't be more proud of everyone involved.

The most recent episode of Reign are available to stream on The CW's site.