Lex was genuinely and completely taken aback by the sight of a mature Galactic Sovereign turtle. Back when he had encountered his very own turtle, it was the first time he encountered a Sovereign, and so he didn't know how big a deal they were - though the subservience of his system was clear at a glance. Sometimes it felt like his own turtle was the real host of the system, and he was just some random substitute.
Later, he learned more. He learned that Sovereigns were greatly beloved by the universe, to an unfair extent. The universe literally catered to their entire whims. Then, as he grew and experienced more, he learned that Sovereigns were actually quite rare, and weren't born randomly.
The birth of each Sovereign required special circumstances, though there was no one fixed formula for their birth. Circumstances that might birth a Sovereign once might never do so again, so they could not be artificially created.
