>>94160245In 1917 she does what Steve tells her to do because Diana is a warrior that understands the concept of taking orders from a superior officer.
She's a fish out of water and understands that this isn't a world she knows or is familiar with, and relies on an outside source to guide her until she finds her feet.
In 2017 we have no idea what their relationship is, because they only have a few short interactions in BvS, and we haven't seen JL yet. But they appear to be more on equal ground, with each one of them taking the lead in several scenes.