If you wanted to know what, exactly, happened between Darkseid and Steppenwolf to result in the latter being banished from Apokolips in the DC film universe, director Zack Snyder has you covered. In the film, it's clear that Darkseid felt he had been betrayed by Steppenwolf -- but that raises almost as many questions as it answers, since it does not seem like Darkseid is the kind of guy to let his betrayers live, whether they're family or not. Snyder had a fairly intuitive explanation for how it all went down, and it even kind of explains how somebody who seems as sycophantic as Steppenwolf ended up branded a traitor at all.
So what did he actually do? Well, it's basically just that he was kind of a lazy military leader and somebody who briefly entertained the idea of a coup, Snyder suggests.
"I feel like there was a coup sometime -- a small coup attempt," Snyder said during a panel at JusticeCon this weekend. "I don't know how involved Steppenwolf was. I doin't think he was like deeply involved or the kingpin, but certainly there might have been a negotiation that he was involved with. He slaughtered those [traitors]; he responded correctly, but in that small hesitation...I don't think Darkseid was down with the notion that there would even be a hesitation."
You can see the video below; the part about Steppenwolf comes in around the 25-minute mark.
In Zack Snyder's Justice League, determined to ensure Superman’s (Henry Cavill) ultimate sacrifice was not in vain, Bruce Wayne (Ben Affleck) aligns forces with Diana Prince (Gal Gadot) with plans to recruit a team of metahumans to protect the world from an approaching threat of catastrophic proportions. The task proves more difficult than Bruce imagined, as each of the recruits must face the demons of their own pasts to transcend that which has held them back, allowing them to come together, finally forming an unprecedented league of heroes. Now united, Batman (Affleck), Wonder Woman (Gadot), Aquaman (Jason Momoa), Cyborg (Ray Fisher) and The Flash (Ezra Miller) may be too late to save the planet from Steppenwolf, DeSaad and Darkseid and their dreadful intentions.
You can see Zack Snyder's Justice League -- in color, or in the black-and-white "Justice is Gray" edition -- on HBO Max.