Such an interesting puzzle.
I know this is common knowledge, but Doc Scratch is so tied to Calliope it hurts.
"His" genetic code comes from the trolls, specifically from two pairings (Team Charge and Team Scourge) plus Gamzee. Calliope likes trolls and shipping them. It also includes the ~ath book! Not the same one she drew in, but still.
What's that? I see. You think you already know my name. You do not know my real name, Jack, just as none of your adversaries on this planet know yours. You only know my nickname.
It's a good nickname too. Befitting of the passive gunslinger charged with initiating the break. I am my master's weapon. His soldier in a war of one bullet fired. But when that bullet clears the barrel, it won't be my finger on the trigger. I'm a facilitator, not an assassin.
"Bluh bluh my name's a big secret and I'm a muse."
Space powers. The revolver. Wearing a coat over suspenders. Never lying. Being overly interested in little girls. Yeah, I know, this isn't news to anyone.
You know how Sburb tries to teach players the value of friendship? I think Caliborn's going to realize how hollow his victory is and accepts a formal surrender from Calliope. They work together to become Lord English, all powerful master of both space and time. It's Lord because Caliborn, the winner, is still in charge. Hence Doc Scratch mentioning "his" master being evil.
So Lord English has all the powers of both, and both weapons, but in the end he really is Caliborn right? Nope. Caliborn is a red herring, and Calliope is a dirty cheater. Perhaps it's the "wildcard" HONK code, or an arrangement with The Felt (who already serve her as Doc Scratch), but somehow she breaks the alliance and takes control of their body. That's why there's almost nothing red about Lord English. Only his cheeks, a detail that Calliope can't or won't correct.
That's my IDE/THEORY and I'm sticking to it! Oh shit another update while I was typing wtf
Edit: Also Cerol kinda ninja'd me. But I made more baseless conjecture, that's worth something right?