The lad had not spoken for a year by now.
He was only five years old, barely able to walk by himself; far too young to understand that his father would not come home,
and Dwalin had no doubts he did not understand the change going through his mother either. It wasn't unusual, for an infant to give up on speaking after a loss such as this.
Especially not in a way such as this; with his father being snatched by orcs during a hunting trip,
and him and Thorin only able to bring back what they had left of him; with the lad stumbling into the room on stubby legs in the worst possible moment to catch a glimpse of
his father's mutilated corpse; with his mother, strong as rock as she was, barely able to take care of herself, let alone of her bairn,
and only to discover she was carrying a second a few weeks after she'd buried its father.
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