Ruby loves Jack and has to be involved with everything he does. Tummy time, feeding time, even just lying around. She's my little diaper nazi, too: in the morning she has to grab all the diapers that I changed during the night and throw them away for me.
And if she hears Jack cry she usually says, "Baby Jack cry! Pacifier!" and then she runs and grabs the pacifier as quickly as she can. She's a girl that loves being a big sis.