#of course other candidates like alvin gerson or dess would give him even more free reign

[stainedglassthreads]

Another thing about the Knight Alphys theory: I just remembered that Alphys is the only character who gets a date/hangout, but no fight scene. We see some bullets from her in the Don't Give Up sequence, as well as the other leads, but Mettaton serves as the final boss for the Hotland area, and aside from instructing you how to use Yellow Mode and flip his switch, Alphys is REALLY absent that whole fight, despite being just as big a presence in Hotland.

Most of the time, to trigger a monster's character develop, and determination to change for the better, you need to have a fight of some kind with them. Sans and Alphys are the only ones where that's not necessary. Sans, because he never really stands in your way, except during No Mercy. And Alphys. Her Hangout happens on its own once you've done the Neutral Route at least once, and afterwards she seems to...work up a resolve to tell the truth. All on her own. Without needing the human to listen to her monologue about her insecurities and dreams as they dodge bullets--all the human needs to do instead is navigate the True Lab and piece together said insecurities and dreams by reading about them in journal entries.

So, again. We see some basic bullets, but never a full fight.

So...y'know...if Alphys does turn out to be the Knight...and she finally gets a boss fight of her own...we'd really have very little idea of what to expect, giving Toby almost a blank canvas in terms of bullet patterns...