Game Of Thrones: 14 Things You Learn Rewatching Season 3
8. Catelyn's Motherless Child Speech Helps Explain Lack Of Stoneheart
During Season 3, Catelyn talks to Talisa about Jon Snow, and how she prayed for him to be taken away from her - and then when he got seriously ill, she prayed for his survival, and says: "Everything that's happened since then, all this horror that's come to my family... it's all because I couldn't love a motherless child."
It's a superb character moment, and one invented for the show - which also highlights how the TV series made Catelyn a more sympathetic character than in the books. This is someone full of love, regret, and a deep-rooted (if little spoken about) faith in the Gods.
When Season 3 aired, it was unclear whether or not Lady Stoneheart would happen, but looking back when knowing she doesn't appear, you can pinpoint this season as a good example of why they chose not to include her. Obviously, there are other factors in there too - scheduling, the story passing to Arya and Sansa etc - but it is also rooted in how her character is portrayed in scenes like this one.