>>720079304
>there is more than one Knight
People have speculated this since Chapter 1, but halfway through the story the game has still not even hinted that this might be the case. Chapter 2 giving The Knight's full title as "The Roaring Knight" opened the suggestion that there might be other Knights with other titles, but Chapter 3 and 4 have made it abundantly clear that The Knight is the one and only Roaring Knight.
>>720080148
>how does one recognize the Knight when one sees them?
King and Queen seem to intuitively know that The Knight is the one who opened their fountains, despite not meeting or seeing them. Jevil and Spamton, characters who inexplicably know more than they should, likewise have some unaccountable knowledge of "The Knight."
Queen is the first to identify them as "The Roaring Knight," despite not knowing who they are or even what "The Roaring" is. The way that a Darkner's knowledge and 'history' is established is somewhat unclear, but knowing that The Knight is the one who created the Cyber World fountain and that each of the fountains in some way reflects the will of their creator, it kind of makes sense that she has some unaccountable intuitive knowledge about this.
In Chapter 3, the only one to mention The Knight is Tenna, because Kris told him about them as part of their "deal." Everyone in the TV World knows Kris, because they're mostly Kris's things and Kris made the fountain.
In Chapter 4, we learn that "The Knight Which Makes With Blackened Knife" is prophesized to oppose The Heroes, reinforcing the idea that The Knight is one individual. The Church World Darkners aren't sure who The Knight is, but they know that there is a Knight.
>>720081393
>>720081630
You can ask questions about why The Knight very deliberately invokes associations with the Holiday family and specifically December but if you don't think it's her, the main question has to be "why would The Knight be impersonating Carol's dead daughter?"