I like this picture because it really sums up their relationship at this point. Milo, as you can see, is a bit blurry, indicating his state of constant motion. Zachary looks apprehensive. He can probably sense that Milo is about to roll right over him or cause some kind of disturbance that will involve some part of Zachary’s body getting squished.
It must kind of suck to be the younger kid sometimes.