We then get Marie's memories of her relationship with her husband's mother, Rushes Bear. As we know from Lulu's account, it wasn't very peaceful, at least initially—it seems that Rushes Bear was kind of a tough customer, and it took a while for her to warm up to people.
However, things seemed to improve when Marie stood up to her, and they found a kind of common ground in the fact that they both felt sad and lonely.
So, things thawed, and Rushes Bear helped Marie have her last baby. Fleur Pillager (Lulu's mother) came to assist as well. This experience further bonded Rushes Bear and her daughter-in-law, and Rushes Bear even went so far as to tell Nector that he was no longer her son (because he was kind of absentee/drunk, which made Marie's life harder); as far as Rushes Bear was concerned, she only had a daughter now (i.e., Marie).
Apparently, Rushes Bear had been particularly impressed that Marie endured a grueling birth without making a peep.