For a long time now, fans have speculated that Kurt Russell would be playing Star Lord's (Chris Pratt) dad in Guardians of the Galaxy Vol. 2. As revealed during San Diego Comic-Con over the weekend, that speculation turned out to be 100 percent correct.

What fans didn't expect to learn was that Star Lord's dad is also a planet — Ego, the living planet, to be precise. The sentient planet created by the legendary Jack Kirby had been rumored to appear in the film for a while now, but nobody picked up on the idea that Ego and Star Lord's dad were one and the same. It's a major change from the comics, but it's one that director James Gunn seems passionate about. He took to Facebook to explain some of the reasoning behind the idea.

"Yeah, his dad is a planet," Gunn writes. "Sort of. It will all be explained in the film ... But to me, this is the absolute center of Vol. 2, and one of the reasons I've been so excited about it. When Marvel first approached me with the first movie, I thought, "Wait a second? A talking raccoon? Isn't that a rather ridiculous idea to base a movie around? It was then that I took a step back and asked myself: Okay, if a raccoon could talk, and shoot a machine gun, how could that be? And answering that question ended up being the entire foundation of Guardians of the Galaxy Vol. 1."

He goes on to explain how Rocket's tragic backstory helped ground the character and serve as an important part of the first film. Some of those same ideas, like the idea of being the only one of your kind in the entire universe, plays into Ego as well.

"Ego seemed, in many ways, like an even more ridiculous character," he writes. "But I asked myself, if a planet was alive, how could that be? And how could it father a child? The answers to those questions took me to a far deeper place that [sic] I expected. I don't want to give away too many answers at this time. But what Nova Prime said about Peter's father at the end of Vol. 1 is certainly true — he is something ancient and unknown. And, as we will discover, being a cosmic being, alone for eons, is perhaps even more lonely than being the universe's sole talking raccoon.

"I can't wait for you guys to see Kurt Russell bring this character to life onscreen. It has been a rapturous experience creating Ego with him. We have both pushed ourselves as far as we can go in making him real, and grounded, and emotionally centered."

It certainly sounds like Ego won't be a mere side character, but a major piece around which the entire movie revolves. Given Ego's size, perhaps that's fitting. Guardians of the Galaxy Vol. 2 is in theaters May 5, 2017.