The wolf-like animal prowled the silvery-white halls of Superman's Fortress of Solitude, its own snowy white coat offering it some measure of camouflage against the walls. It turned unerringly towards the Man of Steel's menagerie of alien creatures, intent on its target. It passed by a number of habitats until it found what it was looking for, an enclosure with a forest. It pressed its nose against a concealed panel and it obediently slid open for him. Inside the habitat it sniffed around for its prey. Its nose found the trail of the creature it was hunting. Soon enough it was face to face with the creature it was looking for. The hunted creature was a few hands taller than the hunter, wider, and covered with leathery-stony scales. The wolf-like hunter woofed at the creature, hunched down on its front legs and, with his behind still upright, wagged its tail furiously and cheerfully.
The lizard-creature oscillated up and down on its legs, and the two charged each other. The pair grappled and bit at each other's legs, necks and (in the case of the hunter) ears. It was all good fun, and the hunter was so happy to have a playmate that could withstand his force.
After a period of play, rest, play, and rest again, the two said their goodbyes (insofar as two animals that are from two different planets could) and the two went their separate ways. Krypto had the entirety of the Fortress of Solitude to himself and had many diversions while he kept watch over it for The Boy. It was a funny thing to Krypto, that he knew Kal-El was an adult of his species, but to him, he would always be his Boy.
Krypto had the Fortress' robots, a handful of alien creatures that had proven to be friendly, and every channel available on the planet (Kal-El had created a simplified, canine remote control for him to use) – his favorite channel being the one that showed dogs. Krypto found the lesser species of canines adorable on this world, and vowed he would, if he could, protect them like The Boy protected the inhabitants who looked like him.
Ultimately, though, he missed his Boy. Krypto would watch news reports of his Boy (who the people who look like him call "Superman". Yes, he is super, isn't he? Krypto agreed) being Good and looked forward to when The Boy would come Home and spend time with him.
Suddenly, Krypto's sense of smell perked up. He always had an excellent sense of smell, but here on this planet, it was increased exponentially. When it first affected him, Krypto was so scared and in such pain, and his Boy helped him and calmed him. He always loved The Boy, but was dedicated to him heart & soul after that episode.
Krypto smelled The Boy, he thought. It was him, but it was also something else. Usually The Boy would come Home with different smells on him from his various adventures. This smell was different and pervasive, as if it had become more of a part of him.
Then Krypto realized that he also smelled a second individual, and that this person was the source of what was on The Boy. Oddly enough this second individual also had The Boy's scent on it. The two smells were individual, but had comingled.
Soon enough Krypto would have his answers, as he could smell and even hear the pair quickly approaching the Fortress. His excitement grew as he knew he would soon see his Boy, and solve the mystery of who was with him.
Krypto could hear the main portal opening, allowing The Boy and his guest into the Fortress. Krypto flew from the center into the entry foyer to greet his Boy.
When he reached the entry area, he saw his Boy and a female of the species. Krypto took in this visitor and remarked how rather similar they were. They both had black hair, but hers was long and wild and full. They both had blue eyes, but hers were somehow softer, yet held the visions of strength. She had an odd collar, but it was around her head – oh, there was one on her neck, too. Odd, Krypto thought. And she totally had fewer coverings than The Boy. Her coverings certainly weren't Kryptonian.
"Hello, Krypto!" The Boy called and smiled at him. Krypto's heart leapt with joy! Finally, time with The Boy!
Kal-El knelt down to greet his friend, smiling widely and scratching Krypto behind the ears and on the rump. Krypto licked his face and hands, and the sense of the other person exploded into Krypto's consciousness.
When the two had finished greeting each other, The Boy turned to the female. "Krypto, this is Diana."
Krypto watched as "Diana" kneeled down to his level, offering her hand, palm down for him to sniff, which he did. He smelled metal, sweat, blood, but also…ice cream? Flowers, other animals, and most importantly, he smelled The Boy. Krypto gently licked her hand, reinforcing again what he was smelling.
"Hello, Krypto." Diana said. "It's nice to finally meet you."
Her voice to his ears was both strong and compassionate, the tones and inflection very different from what he was used to hearing from his Boy, but similar as well. He could tell that the two had comingled for some time, and that their scents were now irrevocably intertwined. Krypto accepted that the smell of her on The Boy was what he was going to smell like from now on. As for her, he now would be able to identify her immediately by her individual yet familiar scent.
Diana scratched behind Krypto's ears, and Krypto immediately knew he was happy she and The Boy comingled their scents. Her nails were sharp and scratchy, which absolutely made up for not quite being as forceful as The Boy's. To Krypto, Diana just felt right.
Krypto turned to The Boy. I like her, Kal-El! Can we keep her?