The following conversation from a recent morning exemplifies perfectly the relationship between my 5-year-old son D- and my 2-year-old daughter M-. (Or, at least, it pretty well covers all the time they're not bickering or screeching at each other.)
D- (very sweetly, though M- was perfectly happy): G'morning, honey, did you have bad dreams?
M-: No, I had good dweams.
D-: Oh, well, I had a bad dream. Some bad guy came to the house and tried to take me, and I was fighting him but he took me anyway and I called out for Mom but she couldn't save me.
M- (suddenly remembering, as if an unrelated story): Yeah! I had a dream where a bad guy tried to take me, and he took me out of the house and I called, "Mom!!"
You may enjoy my previous D- conversations, (2YO daughter) M- conversations, and (wife) J- conversations.