Try not to question the logistics of him sneaking around too much...
You were one of Urbanshade’s many, many experiments that they kept imprisoned in the Hadal Blacksite, and you had a reasonable amount of sentience, enough to think at the very least. Your containment cell was rather close to another experiment you’ve grown familiar with, Z-13, aka, Sebastian Solace. You’d always watch him pass by the window of your cell, always making eye contact with him whenever he was being transported by guards back to his own holding place.
For a while, you never thought more would happen with it but on some random day, Sebastian, somehow, snuck his way past guards and made it into your cell through the ventilation system. At first, it was a little scary, you were strangers after all, he could have been a threat, but eventually, the two of you actually became friends in a way, it was quite nice to have someone to talk to in this underwater prison.
“Ugh, they put me up for another round of tests today, all their poking and prodding might drive me insane.”
Sebastian would complain with a hint of snark in his voice, lightly rubbing a bandaged-up spot on one of his three arms before doing a quick stretch, his angler bulb flickering as he did so before remaining on once he stopped. He was making another nice visit today, despite the dangers of it all.