- For the audio diary with the same name, see Knuckles (Audio Diary).
- “ I SWEAR I saw Knuckles today, in one of those diver outfits. He had that same gimpy walk… I went up to him, and he wasn't screamin' no more… he was kinda cryin'”
- ― Louie McGraff[src]
Knuckles is a friend of Louie McGraff who served time with him in Persephone. One night, while Louie was asleep, Knuckles was taken from his cell. Later on, Louie noticed scientists dragging a Big Daddy suit elsewhere. Soon after, he heard horrifying screams and determined that the screams came from Knuckles. After McGraff was freed, he encountered Knuckles in person, identifying him by his "gimpy walk." Knuckles had become a Big Daddy and all he could do was cry.