Doug Rattmann — known as Rat Man — was a Aperture Science researcher who survived GLaDOS’s neurotoxin purge by hiding in maintenance crawlspaces throughout the facility. His survival is told entirely through environmental storytelling: schizophrenic murals painted on hidden walls, scattered medication, companion cube shrines, and increasingly desperate notes.
The Rat Man dens are accessible in both Portal and Portal 2. In Portal, they appear as small wall gaps and maintenance rooms behind false panels — areas players were never meant to notice. His paintings show the number 42 repeatedly, a Weighted Companion Cube drawn with reverence, and warnings about GLaDOS that Chell could never read.
The canonical tie-in comic ‘Lab Rat’ establishes that Rattmann placed Chell at the top of the testing queue specifically because he saw something in her — a quality he believed could defeat GLaDOS. He saved her life deliberately, then was shot by a turret and placed in stasis, where he survives into Portal 2.
The dens are the purest form of environmental narrative in any Valve game. No dialogue, no quest, no waypoint. Just evidence of a man who lived between the walls and left his mind painted on them.
Didn’t realise how much was hidden under the surface. Makes me want to replay it with fresh eyes.
This is why I always check every corner. You never know what’s been left for the observant player.