i think to say the Brain Ghost Dirk can only exist because of a unique interaction between Dirk and Jake’s powers is misrepresentative of what being a Hero of the Heart aspect really means. while it’s true that the power of Hope is what allows the imaginary to become real, it’s important to keep in mind aspects aren’t just facets of the self, but facets of all reality; in much the same way anyone, Hero of Time or not, can have other selves in other timelines, splinters too are just a fact of existence. the Hero of Heart is just one whose quest is confronting and interacting with those splinters directly.

the very idea of the “Brain Ghost” is a demonstration of this fact. “ghost images” of people and things are sort of recurring characters in Homestuck, usually following an attempt to captchalogue or appearify something that’s not practically available at the time. but what’s important about these ghosts is that even if they’re not “actually”, or physically, real objects, they still carry the same essence; from Hussie’s own commentary, “This is another indication of the fact that [the scribblepad / sylladices in general / Paradox Space as a whole] is dealing in ideas, not material constructs.”

dream bubble ghosts are a further elaboration on this same idea; though they vary in the minutiae of timelines and alternate selves, each ghost contains the memory or idea, and thus true essence, of the “actual” physical body they are the image of. the only difference between this kind of ghost and the “Brain Ghost” is right there in the operative word; these memory-forms exist not as psychic bubble projections, but within the brain of the observer. but the key concept remains identical: just as alternate timeline ghosts may remember events differently but at remain the same person at their core, Jake’s “subjective” perception of Dirk may differ from Dirk’s own “objective” view of himself, but both of them are simply different iterations on the true idea that is Dirk.

which is probably why Heart and Mind form such a close but enigmatic pair! while the Mind aspect concerns itself with the “subject” who alters reality with every thought, the splinters of the Heart aspect are the “objects” which are altered every time they are observed. which is, in turn, probably the reasoning behind the infamous Schrodinger’s Nepeta, the close to 300 pages between Gamzee’s attack and the reveal that the cat is dead. (to take this particular train one station further; this, I suspect, may have also been partial inspiration for Meulin’s mysterious double nature). in a very real sense, the “soul” that the Heart aspect is so concerned with is just another word for an “observation”; a ghost is just one particular “observation” of that character’s life and death. but again, what’s essential here is that just as you don’t need to be a Hero of Mind to alter reality with your thoughts, you don’t need to be a Hero of Heart to be altered; it’s just that these Heroes are the ones with the most potential to observe these phenomena in action!