Portraits revealed through your current reading position.
Juice Box jumped alone into the Nothing believing Justice Light was with her; he stayed behind and lied.
Juice Box escaped the ninth floor by jumping into the permanent portal into The Nothing made from the broken, blood-soaked The Winding Box taken from the Gate of the Feral Gods. Justice Light told her he was going with her. He lied — he needed to be on this side of the veil to activate his trap.
He believed she would be fine if her short time in the Nothing didn't drive her mad. She has a journey ahead of her, but as he told her, if she survives this next part she will be reborn as the ultimate weapon to end this madness and this war. Part of him felt bad; all his friends left in the dungeon might suffer for what he was about to do.
Not seen in this chapter; last known passing through a portal into absolute dark.
The one sent through the Nothing to be remade as the weapon meant to end the war.
Also appears in books you've already read — spoiler-safe to their endings: