In the DC universe what is the relation between Steppenwolf and Darkseid?
In the movie Justice League, we see Steppenwolf mention Darksied in one of his speeches. Also the flying creatures, I believe, are part of Darkseid's army.
Steppenwolf is Darkseid's uncle, the brother of Darkseid's mother Queen Heggra. Darkseid arranged to get Steppenwolf killed in the original war between New Genesis and Apokalips, to help clear the way to Darkseid's taking ultimate power on Apokalips. Once his position was secure, Darkseid resurrected his uncle, who had served since then, primarily as the commander of the Apokalips dog cavalry.