Justice League will introduce Steppenwolf (Ciaran Hinds) as Darkseid's right hand. But if a new report is to be believed, the movie makes a slight adjustment to the supervillains' relationship.
The latest issue of Geek Magazine features loads of new information on Justice League, one article in particular has raised some eyebrows. The article suggests that Darkseid sent Steppenwolf to Earth to regain possession of the three Mother Boxes. But then, it refers to Darkseid as Steppenwolf's nephew (via ScreenRant):
In Justice League, Batman and Wonder Woman, following Superman's death in battling Doomsday, are intent on bringing together a team to take on Steppenwolf. This new menace is the nephew of Darkseid of Apokolips (presumably the big bad of the second JL adventure). Steppenwolf is on Earth to retrieve three Mother Boxes, one of which is now a part of Cyborg.
This may not surprise those less familiar with the comic books, but those who are familiar will surely find it a bit baffling. This is because Steppenwolf is actually Darkseid's uncle in the source materials, not the other way around.
We've seen similar changes in past live-action comic book adaptations, so it's entirely possible that Justice League really did alter the connection between the two supervillains is entirely possible. But I believe that it's more likely that it's a misprint.
Ciaran Hinds suggested in April that his supervillain is "old, tired, still trying to get out of his own enslavement to Darkseid". The adjectives old and tired seem more appropriate if Steppenwolf is the uncle of the ruler of Apokolips, not his nephew. But it's unwise to draw conclusions right now.
Check out this artwork depicting Steppenwolf and Darkseid!