Sealed siblings ending is one of those things that gets more tragic the more you think about it... this time, I was thinking of the fact that Ghost will definitely outlive Hornet. She can’t survive in the Temple, and vessels seem to have unlimited lifespans given that Hollow was evidently to be a permanent solution to the infection. So, she’d pass away eventually, and Ghost would just.. be stuck with her body, until Radiance breaks them, and the whole thing is a futile loss of everything anyway. Or forever, in which case they’d be perfectly hollow, in which case I suppose they wouldn’t care.
I really wonder what Hornet was thinking about during this ending. She wants Ghost to kill the infection outright and not just become a new Hollow Knight, I wonder if she was disappointed? If she were, I don’t think she would let them know.