ok guys y'all gonna hate this one but i had a thought

undertale: well here's the delta rune, it's referencing a prophecy where someone will come down from the surface, the angel, and the underground will go empty. some people think this means the angel will kill everyone and some people think it means that the angel will spare everyone. the fanbase as a whole thinks that it's either chara/frisk or asriel, for the most part, although it's never confirmed. asriel is the only one to get wings, however, and in the pacifist ending is the one who actually breaks the barrier, so there's a good chance that it's him.

deltarune: lmao this one's literally called delta rune, and the prophecy in this one is about some Bad Stuff happening that a) results in the earth being destroyed, causing b) a human, monster, and prince from the dark rolling up and closing the fountain so they can "banish the angel's heaven." the angel. is also here. and also asriel is "at college" and we haven't seen him yet. they stop the angel by closing the fountain.

anyway what i'm saying here is that asriel is the angel in both stories and in this case that'd probably make him the knight as well