Apparently, the Mad Titan isn't the easiest character in the cosmos to write.
Guardians of the Galaxy writer-director James Gunn admitted in a guest column for Vulture called "The Toughest Scene I Wrote" that the introduction of Thanos proved the most difficult.
"There’s pressure with Thanos because you’re setting up this gigantic character that, in one way, isn’t really a part of your movie," he wrote. "His presence doesn’t really serve being in Guardians, and having Thanos be in that scene was more helpful to the Marvel universe than it was to Guardians of the Galaxy. I always wanted to have Thanos in there, but from a structural standpoint, you don’t need him. So that’s part of it, and then part of it is the fact that you’re setting up this incredibly powerful character, but you don’t want to belittle the actual antagonist of the film, which is Ronan. You don’t want him to seem like a big wussy. So how do you make that work?"
Here's how he made it work:
"And that’s why Ronan kills The Other," Gunn wrote. "I thought that was interesting, because we’ve had the Other, who’s obviously very powerful even in comparison to Loki, and then we see Ronan wipe his ass with him. So that I liked, but even that was sort of difficult, because it played as funnier when I first wrote it, and the humor didn’t work so much. But the scene does have what’s probably my favorite Nebula moment in the movie, when she’s strutting out of there saying, 'Thanks, Dad.' And she’s also saving Ronan’s ass, because she knows that Ronan’s a hothead."
Gunn is working on Guardians of the Galaxy 2, which is scheduled to fly into theaters on May 5, 2017.