Here are a couple moments I enjoyed.
Michael woke up before Sophie from their morning (and afternoon) nap and led the way in when she called for us.
It's amazing how quickly he can crawl, even in his sleep sack.
Sophie, for the record, is pretty much crawling as well. She only takes a few "steps" at a time and then seems satisfied to sit and play, but she has the basic idea.
And here's a typical sock situation around here these days. Sophie--zero. Michael--four. Sometimes Sophie has one on her foot and one in her mouth. Sometimes they both only have one on and the other two are who knows where. They'll hold onto socks through feedings, crawling, and while playing with other toys. They just love those things.
Similar transactions take place with pacifiers. For example, I might look in at two babies in a crib during a diaper changing to find the "boy" paci in Sophie's mouth and a "girl" one in Michael's hand, not sure whether it was a trade, revenge, or part of some game I'm just not young enough to understand.