Subtle Melancholy
Addam wanders, and wanders, and wanders some more.
He is a man for exuding his pent-up energy, doing something with it most expediently because he'd much prefer that than to have to sit with it while he examines it - if, that is, he examines it at all. More often, he simply...realizes it later. In eventuality.
And Ziggy does not follow him. It would make too much noise.
Well. There are an abundance of reasons. But mostly, he is private enough himself to let Addam return to him, disease managed, in peace.
Composed.
On his own terms, as it were.