I also think it would be good to add an Ending Monologue if the game has finished, and the floors have been completed.
If there isn’t one already, the storyline could possibly imply that Patient Zero was really the one creating everything, the monsters and such (in some way)— but had only remembered after escaping the place, and understands it fully.
It could be something like this, similar to the first beginning dialogue:
“When things stay in one place for too long, they perish, they rot.
And so I, Patient Zero— who had once been locked under inevitable stillness— have deteriorated, entirely.
The core of the hospital I must be, holding up what remains of its legacy…
I have been there since the start, that is who I am, now.
So as Patient Zero, the very foundation of the place… I had formed everything, torn it apart at the seams, and taken my leave.”