BtVS/Angel by Whedon and Mutant Enemy. Tarzan by Edgar Rice Burroughs. The fable here is adapted from one retold in an episode of Star Trek: Voyager. It's definitely like Aesop, but the exact origin's hard to pin down.
Coastal Africa, 'Hollow-Earth'
Connor, feeling ignored, let loose another wail. He missed his home and his odd family. Mid-cry, he coughed, releasing a puff of golden radiance that hung about his head in a bright halo. Entranced by the cloud of sparkles, he quieted down and soon drifted off into slumber.
Catching Tarzan's gaze, Holtz shrugged as well as he could. "Don't ask me, he's been doing that for two days. They've been tapering off." Remembering something that had been bothering him, Holtz put together a cover story. "The first one was much larger and must have affected us, or at least my mind, somehow, as the next thing I remember, we were by the earthen drum over there. I've been trying to cut a path to civilization since we arrived, but the best I've managed through the vines and the creepers and these damn trees is to reach a trickle of water. How did you find this place? There a path through one of those hills?"
Tarzan laughed and pointed upwards. "I'm afraid that my tribe congregates here because there is no decent ground route until much further out. Unless you can manage to pull yourself to the canopy and step from branch to branch, you may very well be stuck. Myself, I swing freely through the trees, a skill that I find sorely lacking in civilized places."
Holtz chuckled softly. "Seems like we might have more in common then we thought. I apologize for the short stabbing. You have to understand that I am protective of my son and your odd manner of dress was not reassuring in the slightest." He gave a short smile and flexed a bound arm slightly upwards. "My name is Daniel and the babe over there," he said, having already decided on Connor's new identity. "Is Steven."
If he'd managed to escape with Justine and Connor as planned, Holtz would've made them a proper family with a new last name to prevent the paper trails of the modern world leading directly to them. While arriving through a portal implied that being tracked was the least of his worries, he was putting off telling his full name until he had a better feel of what he'd landed in.
Grinning freely as he sat down, Tarzan nodded in the direction of the coast. "I am Tarzan of the Apes and, yes, I'm afraid I've gone and left my freshly pressed suit back on my ship. I'm here on my own errand, which I'd rather perform while not under the scrutiny of someone who has freshly raised a weapon against me, even with the understandable circumstances."
Tarzan scratched his chin in thought. "Seems that here, especially bound, you'd be easy prey for any ape that happened across. There is a cabin a short distance away from where my boat lies in anchor. You are welcome to use it until we are ready to leave. I only ask that you leave your weapons here so that I may later retrieve them and disarm any traps you may have set. My people and their children often play here, no need to leave surprises for them."
Through careful application of woven ropes and cloth an adequate harnessing system was created for Tarzan, with his immense strength, to safely bear the other two with him through the branches of the trees.
"It is some distance away," Tarzan said as he carefully avoided the tree where he'd hidden his digging spade on hearing Connor's cry. "So I must ask for your patience. We'll stop at some point after the brush thins out, so you can stretch a bit."
Holtz passed the time staring deep into the jungle. After awhile, he spoke. "This reminds me of the tale of the Frog and the Scorpion. There was a Scorpion who could not swim who had been forced onto a small island by rising waters and soon even that would be lost. A large Frog happened by and seeing that the only thing separating the Scorpion from safety was, from his perspective, a small stream, offered the Scorpion a ride on his back. Half-way there, the Scorpion stung him so they would both drown."
His arms and legs not missing a beat in their dance through the trees, Tarzan spoke up to finish the story. "And when the Frog asked why, the Scorpion replied, 'because it is my nature.' Many fables were among the books I taught myself to read on. The tales of Aesop and those inspired by him were some of my favorites. It took me years to work out that the idea of animals having a language in reality could be seen by others as strange."
"So, Daniel," Tarzan continued with a dark chuckle. "Keeping in mind that the noose could as easily have wound around your neck as your wrist and I chose the path of least harm, I have to ask. What is your nature?"
Holtz stared into the lengthening shadows as night slowly fell, his mind on the family that Angelus had stolen from him so many years before... "I had a drive, an ambition, which was paid for in the blood of my family when the murderers I sought to bring to justice decided they were too tempting a target to pass up. My nature is a weapon and I dream of honing my son into the tool I should have been, something that could have saved his mother, his twin brother and the elder sister he never really had the chance to know..."