in circumstances like this we might be logically expected to take the route of assuming that there is no defined soul in Homestuck and, just like in real life, we’re expected to philosophise over the meaning of the soul for ourselves. but we can’t begin to understand Dirk’s role as a prince of souls without this basic foundation…
the main clue would seem to be in Dirk’s enthusiasm for Plato, who had a very clear idea of what the soul was; but Plato’s soul was the invincible idea, which in Homestuck is called the ultimate self. and Book 6 has already given us that clue that in the dream bubbles, “memory of someone [is] linked to the truth of that person’s existence”. so we come back around to soul-as-memory.
i’m sort of overlooking forest for trees here: the very name of the event, Remem8er, is screaming at us that memory holds significance here. so why should it also be revealed in that same animation that memories are meaningless - that just because you have the memories of an event, doesn’t mean it “happened to you”?
and this is a flash about Terezi, whose very “deal” is her ability to see how perception shapes reality rather than the other way around. can we take the collapsing Mind neuron at the end of the animation as indication that events depicted are perhaps not exactly as they seem, at least in the alpha timeline?