On the page, Cersei's story to youngest son Tommen is little more than a poorly-veiled metaphor about Lannister supremacy (and Tommen's true paternity). As portrayed in "Blackwater," however, the story is Cersei's attempt to keep her son calm as a terrible battle wages around them. Throughout the story, she is unstoppering a bottle of poison and preparing to dose both her son and herself rather than submit to capture at the hands of Stannis Baratheon. As Cersei is more than aware of what happened to the royal family the last time that King's Landing was sacked, we can't really fault her for wanting to spare Tommen (and herself) the fates of the Targaryen women and children. After all, as Tyrion says, Cersei's one redeeming quality is her love for her children. Of course, Tywin Lannister arrives to save the day and prevent Cersei from poisoning her son, but her speech remains as possibly her only truly sympathetic moment in the first two seasons of the show.
Fiction buff and writer. If it's on Netflix, it's probably in my queue. I've bought DVDs for the special features and usually claim that the book is better than the movie or show (and can provide examples). I've never met a TV show that I won't marathon. Follow on Twitter @lah9891 .