I wanted to embroil the children in something larger than themselves, as they were in the story - not merely to show them fleeing from some undrawable "baddie." The antagonist that Meg, Charles Wallace, and Calvin face is depicted simplistically in the tale (simply referred to as "The Black Thing") but it collectively refers to anything springing from the worst aspects of ourselves: our fear, our hatred. The Black Thing is in us, in the children. It sings its own song. It caresses.
Above, in the stars, hover the shape-shifting, time-bending entities known as the Mrs. W's (Whatsit, Who, Which). Although they twine tendrils down among the children, they're held at a distance, fundamentally removed. Etched in starlight, they watch protectively, but leave the children to face their challenges alone. They're lit with starlight, bannered by hints at their angelic nature.