Jayce, Viktor, & Nautilus
From Jayce and Viktor's lore:
This came to a head during a reluctant collaboration with Jayce to improve the diving suits used to keep Piltover's docks clear of underwater debris and lingering chemical waste. Viktor and Jayce's enhanced suits allowed the wearer to go deeper, remain underwater for longer, and lift heavier weights. But many wearers claimed they saw phantom corpse lights in the depths or suffered from chem-induced hallucinations. When divers experienced such symptoms, they panicked and often got themselves or their fellow divers killed. Viktor saw the problem was not technical, but with the wearer's nerves unraveling in the inky depths. He devised a chem-shunt helm that allowed an operator on the surface to bypass the wearer's fear response and, effectively, control the diver. A heated discussion between Viktor and Jayce on free will and mental enslavement turned bitter - almost violent - and the two vowed never to work together again.
This makes me wonder.....
What if, in a revised Lore -Nautilus was one of these divers?
And his specialized suit was one of these designed by Jayce and Viktor?
This also begs the question what if....they weren't hallucinations, but something else?
Or even if they were, what if there were unforseen consequences, much alike Warwick under the experimentation of Singed?
Then there is the possibility that the strange black ooze in Nautilus' lore was some kind of Chem-tech waste. Such material may have created the likes of Mundo, and Zac based on their lore.
He could have been abandoned and left for dead.