Dietrich and the dog bonded over the days after the ammo dump's explosion.
The dog – he never really figured out a name for it – was there after his commanding officer threatened to send Dietrich down in the ranks, ship him off to the Russian front, and any other number of terrible things. Including a visit from the Gestapo to make sure his loyalties weren't waning.
Of course they weren't. He'd never go over to the Allied side.
The dog was there during the long, cold nights when nightmares haunted him.
The dog was there when his men needed a morale boost.
And the dog was there when he got a letter saying his father had died.
All in all, the dog was a better friend than most people he'd come across.