When I first adopted Loki, his foster gave me a list of words and commands he understood. "Mine" was one of them. Basically, he understood the difference between what belonged to her and what he could have.
Like most GSDs, Loki enjoys possessing things but never puts up a fight when told something doesn't belong to him. And like most GSD's, he's also a "leaner," pushing his body against any person he likes.
At the end of a playdate with our neighbor's puppy Aslan, Loki's biggest fan and favorite pal, Ludwig, came outside to say hello to all the dogs. Loki recognized him and got up to go say hello. Juno wasn't far behind. Loki reached Ludwig, checked in then immediately turned around and chased Juno away.
"MINE," he said to Juno.
As adorable as that is, that small, benign behavior could easily escalate into stronger more undesirable behaviors in a dog like Loki. It's times like this, I realize how fortunate Loki is to be owned by an adult who teaches him to share.