Yall I have had a moment of realization
What if “older” Brinearr take younger Brinearr under their wings when they first amalgamate so that they can help the younger Brinearr kind of figure out the swirling thoughts, feelings, emotions, histories, of 6 or so different Einarr.
So when Guthrie was referring to his “mom” he was referring to the Brinearr that took responsibility for helping him adjust to this world who the two of them thought “mom” was the best title for.
And then “stepdad” is another older Brinearr who also stepped in to help Guthrie adjust to his new life and potentially has a relationship with “mom”
And this is just a new and beautiful family dynamic that has occurred by necessity in Founder’s Wake with all the new Brinearr
And maybe the reason Zoox is not as well adjusted to life and keeps asking clarifying questions and doesn’t really have concrete pronouns is because when they amalgamated they didn’t have an older Brinearr to guide them or maybe they had to separate from their Brinearr guide and so they’re looking for help from those around them
And why Guthrie could tell immediately that Zoox was newly formed and was softer with them