
Featureless Protagonist: Originally, until recent versions completely subverted this by giving him a name, age, appearance, and backstory. He Knows Too Much: In one ending, D-9341 is kidnapped by the Chaos Insurgency due to what he's witnessed throughout the game. The player is much more scared than D-9341 ever is.
Death simply isn't that scary to someone who's experienced it multiple times.
Expendable Alternate Universe: A likely explanation for his success in (eventually) escaping the facility, and for his suicidal recklessness. Everyone Has Standards: When ordering drinks from SCP-294, hes willing to drink cups of molten lava, bleach, nuclear energy, and SCP-106s corrosive slime, but he draws the line at drinking bodily waste like semen or feces. In fact, his luck is SO prominent and almost paranormal that the Foundation considers registering him as an SCP in one ending. Born Lucky: In-universe, this is his primary trait. Including his name, where he is from, or anything. Amnesiac Hero: He has almost no memory of his life before he awoke in a cell inside the facility. Subverted in that he does have a special power The Spiral Gestalt he just doesn't remember that he has it. He has no special training or skills to help him escape. Action Survivor: He is just a random guy, thrown into a nightmarish hellhole. It's revealed that he was actually once a Foundation scientist demoted for unauthorized research. The Player Character, an unwilling Red Shirt of the SCP Foundation's immoral experiments.