Siblings are really so much fun to observe. Brothers are so much fun to observe. I've never had a brother, but when I watch these two I can see that what they experience isn't all that different than watching my girl with my boys, or even remembering my childhood with my sisters.
Every day is filled with thousands of tiny adventures. Things to explore, things to try. Places that have been visited with regularity are made new each time with the fresh perspective of growing eyes.
And when one strikes out to explore on his own, he's still sharing the experience with his siblings.
Because when you are growing up with brothers or sisters, you aren't ever really alone. They're there. Even if you don't see them.