Sarah is the diva of Israel. Her big claim to fame is that God chooses her (over all of Abraham's other wives) to be the mother of the deity's favorite nation. Way to go, Sarah.
This lady is the star of several shorter episodes in the Abraham-cycle. Typically, she's cast in three quintessentially female roles throughout Genesis:
Life isn't always easy for a stereotypical woman in Genesis. See, God promises that she'll be the mother of God's special nation. But here's the thing: she's barren and super old. In fact, the whole thing is so implausible that Sarah and Abraham find the whole thing pretty hilarious (17:17; 18:11).
After she has a good laugh, she takes matters into her own hands. Her hubby needs a child, so she's going to get him a child. Well, that's at least her plan in Genesis 16, where she hands her own slave girl Hagar over to Abraham, saying, "it may be that I shall obtain children by her" (16:2 NRSV). Whatever works, we guess.
Everything goes as planned, and Hagar has a son named Ishmael. Just one problem: Sarah did not anticipate the family-drama and serious rivalry that would result from her promotion of Hagar, who takes a big step up the career-ladder from slave to wife with a son. Oops.
Faced with a serious rival, Sarah again does what any diva would do. She tries to demote Hagar and ruin her new-found status. Once Sarah persuades Abraham to put Hagar under her control as she was before, Sarah maltreats the poor woman, who's suffering so badly that she runs away with her child (16:6-7). And you know what? That was probably Sarah's intention all along.
Even after the post-menopausal birth of Isaac, Sarah still has work to do. She knows that it's through her son Isaac that God has promised to make a nation. But there's still this Ishmael around messing things up. Sarah wants him out of the picture so that her son can be the sole heir of Abraham's estate as well as God's promises. She's a pushy mom now, with some clout as a wife with a son, and so she orders her hubby, "Cast out this slave woman with her son" (21:10 NRSV). Abraham is hesitant, but God tells him to listen to Sarah (21:12).
Wait, what? God approves of this? Well, the promise has got to come about somehow, right? Sometimes it just takes a diva or two to get the ball rolling.