Portraits revealed through your current reading position.
Sadistic card-master who stole Carl's stairwell key and got killed for it.
Quan was, in Quasar's assessment, "this little ass-smear of a prick" — a sadistic crawler measured against Tempest's grandmother and found only slightly less awful.
On the eighth floor, Carl's team was thoroughly wrecked by the system's card rules and looked likely to miss out on a key to the next floor entirely. Quan made it worse deliberately: he stole Carl's key, which meant Carl "pretty much had to kill him". The killing was clean enough in the system's eyes that Carl walked away without a player-killer skull — a detail Quasar specifically flags, since a skull would have followed Carl into Faction Wars.
Not described in the recap; characterised entirely by cruelty and pettiness, and compared unfavourably to a relative of Tempest's.
The eighth floor's key thief, whose death gave Carl a kill without a penalty.
Also appears in books you've already read — spoiler-safe to their endings: