Yo it would be totally so swag and awesome sauce if you talk about Dio's radical origins bro
Doesn't have to be in totes detail but where did he come from you here me?
OH WONDERFUL QUESTION! The world which DIO originated from was called Teknopolis, a technologically-enhanced utopian society (with a dystopian underbelly that most seem to live in ignorance of...). Everything and everyone in the world are interconnected by a network of code, which is looked over by a deific AI simply known as MOTHER.
Very little of the world resembles how it appeared prior to the mass technological advancement. The only nature that remains surrounds the world's secondary "tower," an ancient tree that mirrors the world's other tower (the tallest structure in the world, where MOTHER is located).
As for DIO in particular...
DIO is sentient malware; a virus, a disease. A parasite in need of a host. They once dwelled within the world's code, beginning their existence stewing in spite and jealousy of the Teknizens and fleeing from being exterminated by MOTHER. They only escaped her wrath upon finding a host to infect, overtake, and manipulate. I will keep their host's identity unknown for now, but their mysterious disappearance acts as the catalyst for Teknopolis' story.
DIO gains a physical form after making their host drag themself to the world's secondary "tower," leeching off the surrounding life energy in order to break through the realm of code and into reality. Not without negative effects and sustaining a dire wound (which is what the scar on their abdomen is from), but they lived nevertheless. Pain as a sign of living, of being real.
It didn't take long for DIO to begin questioning their existence, feeling disconnected with the world they willed themself into. They did not belong. Deemed a fault in the code, a mistake, for what purpose did they exist? Did they even have a purpose? Most viruses are man-made in their world, engineered by the hands of Teknizens. Yet they had no such creator.
They were the manifestation of entropy in an isolated system. The inevitable spiral of their technology-dependent world that forgot how to form genuine connections long ago.
It was at their most troubled that DIO was beckoned by a mysterious force. They were promised a purpose, a fulfilling existence within solitude. And who was DIO, an opportunistic organism, to deny such an offer?
That was when DIO met Reclusa, who sought a vessel to gather energy for him as he incubated in his egg. That was when DIO formed a plan to use Reclusa as a host after he hatches, witnessing an entity holding more power than most could fathom. The virus' inherent hunger for more never stopped, it only grew during their time debating how they could make a place for themself in their hopeless world.
Why do they exist if not to thrive, after all...?
Reclusa knew DIO's plan from the start, of course, as a being capable of reading and twisting thoughts as he pleases. And he allowed them to follow through with it. Another source of motivation for them in tandem with his manipulation! It would be so much fun to build their ego up just to knock it down again! He found their mindset thoroughly entertaining.
They stood no chance against him. Their plan to infect and overtake Reclusa predictably failed.
That was the beginning of the end. No particular duo of plumbers in Teknopolis to lift a finger against the slow and meticulous severing of everything and everyone. Only futile attempts made by those with hope in their hearts.
But there was no denying that Reclusa technically fulfilled his promises to DIO: he did give them a purpose. They continued to be useful to him, and in return he slowly claimed them for himself. They would eventually truly become part of his isolated conglomerate of solitude, a part of Reclusa.
All while DIO watched their world end at the solitary claws of the manifestation of loneliness. And would watch countless more end as they became entangled in his cyclical existence. A perfect little host for the isolated energy that sustains the eldritch entity.
They're such fun to play with, after all. His favorite toy whose sole purpose is to continue benefiting him alone. And who are they to complain? They've never felt so...content. They realized how unhappy they would have been in Teknopolis, even after usurping MOTHER.
Maybe solitude truly is sublime.
Thank you so much to @darknoverse for the Teknopolis concept art, animation, and doodle hehe :]