Nymphadora Tonks was the only one who was willing to take Sirius for a walk with the only condition that he must wear a leash like a normal dog.

One day, while they were walking side by side under the trees of a beautiful londoner park like a pet and its owner, Tonks decided it was the best moment to tell her cousin she was in love with his best friend.

He wouldn't be able to make fun of her if the only thing that could escape from his snout were barks.

After a very long walk, they went back to Grimmauld Place but he didn't say a word when he changed back to his human form. He just smiled at her in silence.

When Sirius died, Harry inherited most of Sirius' belongings except one thing, the little name tag he always used during his strolls with his first cousin once removed. Tonks kept it as a symbol of their friendship and wore it like a necklace until the day she passed away.