Wherever (In Origin, at least) there was lava, there were lava rats. The moment Callum dared to delve into the smoke-choked, steaming heat of the Underforge, or the lava rivers cascading through Leo's connecting tunnels, he would find what he was looking for:

The mineral-encrusted, bone-thin bodies of a small family of lava rats. What with the smoke and trembling earth, and air shimmering with heat, he saw them before they'd see him. There were seven in total, a couple younger ones, a few older, foraging around the rock and digging for scraps of metal and food. They were all, even as a group, fairly small: likely even all seven couldn't pose a real threat to the hybrid dragon.

One was, indeed, closer than the rest. This one looked somewhat older, crossed with scar tissue, one flaming eye gone milky with blindness. And it was farther out, so that if he were quick, Callum could snag it and go.

However, there were two caveats with this. First, their body temperates were near-boiling--searingly hot, adapted with mineralized blood to withstand tissue damage. In other words? It'd probably hurt Callum's skin to touch it, once he'd made his pounce. Second, he might now notice that these rats were enormous compared to the mouse he'd caught. It was far more likely to eat a mouse than crossbreed with it, but... if he didn't mind losing a few test subjects in the process, it couldn't hurt to try. Right?

Well, maybe a little burning, but perhaps Callum could find a way around that.

@Callum

He had found not one, but seven lava rats. To smaller gembounds this might have been a rather scary situation, but Callum didn't mind at all. No matter the number he could easily beat them up. But that wasn't what he was here to do. His gaze fell on the rat closest to him, which he decided would be his target. Before he acted, however, he would need to protect himself from the burns he may gain. A small tingle spread from the raspite and through his paws, shielding them slightly from the heat.
The dragon snuck as close as he could before quickly running forward and pouncing onto the lava rat, using both his paws to pick it up before it could escape. The spell protected him slightly from the heat, enough so that he wouldn't get burns, but it still hurt like hell to touch the rat. He transferred it to one paw and awkwardly walked back to the enclosure and dropped it in.

The mouse had, like any wild animal, hidden in terror. Upon Callum's return it was crouched--trembling--beneath the scavenged plants.

The lava rat, on the other hand, was hysterically aggressive--twisting and biting at the paw that held it. When at last it was dropped into the enclosure, it proved its ability to leap terrifyingly high--about six feet straight up--but the well-stacked rocks, smooth as they were, kept it sliding back down.

That didn't mean it gave up. It wasn't a domesticated creature, and every instinct screamed for its escape, rather than allowing it to simply stay here and enjoy its cold-aired, shelterless captivity. Fangs were bared any time Callum grew close, the half-blind old beast full of fear and fury.

For now, Callum would be stuck with two creatures: one hiding, the other panicking in its attempts to escape.

This would likely last a few hours--the rat exhausting itself completely before also crawling beneath the plant. At this point, it ran into the mouse--and, being a rat, immediately and savagely attacked it. The mouse squealed and bolted. The rat--having tired itself out--didn't pursue for now, but the mouse now took its place in panicking: running from side to side, bleeding from its flank, desperate to find an escape.

@Callum

Callum couldn't help but feel a bit bad for the mouse- even if it was a lesser. He had tried so hard to ensure they would be friendly with each other! He had even provided them with food! Then, perhaps, it had to be something else motivating the rat to attack the mouse. It was not for the sake of having prey to eat. Then what could it possibly be? The dragon thought about this as he watched the rat continue to pursue the mouse around the enclosure.
He thought long and hard about the whole thing, investigating their behaviors, and trying to discern what the solution to the problem could be. Was the lava rat way too big in size? Should be find a smaller lava rat? Or was the problem because he didn't have time for them to get accustomed to each other? If it was instinctual it would be considerably harder for it to work out, because the rat was old and probably set in its hatred of mice. And now it had traumatized the red mouse so much he wasn't sure if they could work out at all.

The rat was highly stressed, and--in the end--a rat. The way it had gone, without hesitation, for the mouse (despite all else troubling it) made it clear that this one was indeed an instinctive behavior. It was almost hatred.

Perhaps two critters who naturally got along, already, might work better; and even so, Callum would need to settle in for the long haul, long enough for them to go about their life cycles and settle on one another as partners. As it was, these two might settle over time--but more likely, the mouse would be eaten within hours.

Did Callum have the patience to tame Lessers, to provide them a fine habitat and periodic food and water, to give them shelter and to protect them? Perhaps he could be the first mad doctor to create such hybrids, but as it stood, it was clear the rat and mouse were a poor first prospect.

@Callum

It was unfortunate that his first trial was clearly a failure. But he had a new idea. He would have to start from scratch- in terms of lessers of course. Reaching his paw into the enclosure, he snatched the red mouse and placed it on the ground outside, allowing it to run free. The red mouse was bound to die sooner or later, but he wanted to give it a chance at escape anyways. He waited a minute before wrangling the lava rat out too and releasing it. Now that the enclosure was empty, it was time for a fresh start. But first, he would have to go fill up his stomach. It was clear no hybrid prey would be coming anytime soon.

Exit Callum