The black water is sentient, and is forcing its way down OPs throat to impregnate his stomach with little black water eggs.

Alright I have no idea about anything, but I read your post and my first thought was “good question, but wouldn’t local interactions be identically impacted by expansion, thus negating expansion as a variable?” In other words: would it not be a constant applied to both masses?

Unless the local bodies are 2 different galaxies, in which case now I want to know too.