After all these promises from God, Sarah started feeling really bad about being barren, so she told Abraham that he could fuck her slave woman Hagar, and she, Sarah, would claim any resulting children as her own. However, when Hagar did get pregnant, Sarah just hated her for it and accused her of being proud and insolent. She started beating Hagar and accusing Abraham of liking Hagar better.
It got so bad that Hagar finally ran away, but then an angel came to her and told her to stiffen that upper lip, go back and submit to all the abuse Sarah could dish out, because if she did, then God would bless Ishmael. So Hagar stupidly returns to an abusive situation, and maybe Ishmael was blessed, but his descendants mostly show up in this story as adversaries to God’s favorites, the Hebrews who descended from Isaac.