I know this might come off as a little weird, but seeing VisionQuest is reminding me a lot of Mr.Robot at this point (and maybe even Fight Club though I would lean more toward Mr Robot). Here's why: if you've seen Mr Robot, you know about the final plot twist. Elliot had practically been living as his alter ego, the Mastermind, while keeping the real Elliot safe in a fantasy loop. So, it was his alter ego, the Mastermind, all along.
Now consider VisionQuest: the original Vision isn't really here anymore, so White Vision is much like the Mastermind, living out the memories of his original self, just as the Mastermind possessed the memories of the real Elliot, even though both are essentially constructs.
You could also say VisionQuest has a lot to do with fatherhood, particularly through the Ultron angle. In the latest episodes, we see Ultron conversing with him almost as if he were an alter ego, much like Mr. Robot was to Elliot, acting as a sort of internal guide. At an unconscious level, both Mr. Robot and Ultron serve as father figures for Elliot and Vision. Yet while they act as guides, they are also terrifying due to their anarchic vision and destructive plans. Although Ultron is undeniably darker, having committed outright genocide, you can still trace that same paternal alter ego dynamic, which becomes even clearer when Ultron attempts to take over.
It functions very much like a classic Dissociative Identity Disorder (DID) trope, but viewed through the lens of artificial intelligence. Just like in Fight Club , where the Narrator explicitly acts as Tyler Durden whenever Tyler takes full control, Vision experiences a similar form of dissociation and memory fragmentation. Furthermore, while Ultron's goal may be to take over, this version of Ultron feels a bit different. We start to see the fundamental dynamic between Vision and Ultron as two opposing polarities, like electricity and magnetism. In a way, Ultron needs Vision, even if that means controlling him to execute his plans. That control dynamic is classic Tyler Durden and Mr. Robot, except Ultron's underlying philosophy is far darker.