After our daughter was born, it was heartwarming to see him tend to his baby sister. He gave her a pacifier or pushed her swing when she cried. Sometimes his help was met with smiles and giggles and other times our daughter continued to cry or flailed her arms in protest. I felt terrible that I wasn't able to fully prepare our son for just how difficult it can be to calm a fussing baby.
As our daughter approaches her first birthday, our kids' relationship is ever changing. Sometimes our son calms his sister's cries. Other times they play side by side as play mates. And other times I spend most of my energy figuring out ways to keep the peace.
I'm sure their relationship will only become more complex as our daughter becomes more mobile and more vocal. But I am very excited to see what happens as we welcome the toddler years a second time around.