Sibling chivalry?

Since the day we came home from the hospital with Lillie, Parker has taken it upon himself to hold her hand in the car. It is the cutest gesture and we never ever prompted him to do it. Everytime we get into the van Parker climbs into his carseat and I put Lillie in hers. Within seconds of starting the car Parker holds onto her right hand and holds it until she falls asleep. Then he goes on with eating his snack, reading his books or playing with one of his toys. If she starts to cry or fuss he puts whatever he is playing with down and holds onto her hand again. It's adoreable and I cherish the moment everytime I see it.