Dream's Behavior And Actions
Dream's imprisonment was far more traumatizing than he lets on nor does anyone actually notice. His actions after returning to the Dreaming, was just him trying to maintain control after losing all control entirely and in trying to maintain that control he shut everyone out and tried to force things back into the shapes that they were in when he was in control over a hundred years ago. Over the course of the show, we are shown him healing from his century of confinement. In doing so he is slowly realizing that yes he went through something awful but also no he's not alone and there are plenty of people around him who care about him and will do everything they can to help him out if he just listens to them.
He thought that that was what he had to do in order to feel safe and in order for things to be normal again. The more he tried to do that though the more things got worse and clearly that meant that in order to fix things and bring about that safety/control/sense of home that he so badly needed, he had to face his own nightmare of change, and then change with those around him like they had so long ago when he left. No man is an island but Dream certainly tried to be one. Until of course, he saw everyone else around him working together and changing and succeeding in ways that they were never originally designed for while he tried to stay apart and kept failing.
He had his own epiphany then and went through his own kind of transformation. Bit by bit we see Tom Sturridge altering Dream's characteristics. A smile here. An apology there. A moment where instead of talking over someone he was quiet and let them speak. A few others where he paused and gave thought to things when he otherwise would've acted swiftly and decisively. It was all a transformation personified in that one singular at the end.
Dream changing Gault into a butterfly wasn't just about him owning up to his mistakes and asking for forgiveness from everyone but it was more of a literal representation of how he had once been a caterpillar that was pulled into a chrysalis and underwent a metamorphosis of his own into a beautiful brand new butterfly in his own right. Since the Dreaming is him and he is the Dreaming, this also meant that everything and everyone around him was free to change as he had.
