When we asked a Magic 8 Ball for its opinion on this, we agreed that whatever it answered would be worked into the story. Here is said answer, and the joke it inspired.
Despite being a bit lighter in the bag, Diana was not at all lighter in the heart as they continued through Poni Island, traveling in places that they had never traveled before and trying very hard not to get lost. Finally, thanks to Rotom's map feature, they found the cave.
"That took forever," Diana commented, as casually as if they weren't about to track down one of the most dangerous UBs they'd heard of so far. The cave was almost empty, and the rough terrain that most people would summon a Mudsdale for was treated as a minor inconvenience.
"I can't believe you're calm about this," Eli said, not impressed at all. "This thing killed a woman, remember? And we're just kids. We're going to die, Diana."
"We don't know that," Diana objected. "We just know it's a very real possibility. And if I'm putting my life on the line for science, then I can accept death."
"Trust me," Rotom interrupted, "she can."
Diana smiled, recalling when she had been willing to surrender in the middle of a forest to see if she'd become a Phantump.
A strange sound came from somewhere in the cave, echoing off the walls and making it impossible to determine where it came from. They both stopped, holding their breath in anticipation, but when they didn't feel the breath of a beast on their backs, they continued.
Then it happened again.
"What is that sound?" Eli complained, looking around and trying to pretend that he wasn't ten seconds from a panic attack.
Diana frowned, tapping a finger on her lips. "It sounds like someone's frying bacon," she decided, "while smacking their head with the pan."
The sound happened again. "You're not wrong," Rotom admitted. "But it sounds more...growly."
The noise happened again. Whatever was making it, they were getting closer.
Another five steps. Another sound. Twelve steps. Sound. Eight. Ten. Fourteen.
When they reached the cave wall, and found that there was nothing on the one side but more wall and a large hole, Eli groaned in exasperation.
"Ok," he said, gritting his teeth. "Someone better tell me what's making that noi..."
The word turned into a squeak as he made the mistake of turning around. Diana and Rotom, reluctantly, followed suit.
They found themselves face-to-face with a gigantic monster, a disproportionately small head on top of a huge, round body that seemed to have another face on it. Black and yellow (Dark/Electric? Rotom wondered through his fear) and bright blue.
The belly opened up, revealing an endless cavern filled with what could be teeth and an extra set of claw-tipped arms as tongues.
"That isn't real," Eli said quietly, as he forced his eyes shut, pretending denial would make it go away.
Diana knew better. She had been afraid before. The Nihilego that had come to Alola, the very first UB mission. The Nihilego swarm on their trip to space, one fusing with the woman it had already drugged to insanity and the others singing backup acapella.
The absolute terror of those incidents was nothing to her now. She would rather fight Lusabeast again than face this thing for one more moment.
And, as the chill running down her back turned into a proper shiver and her blood felt like slush, she had never felt more alive. Her heart, pounding so hard it was almost painful, caught in her throat as she prepared to send out Bewear.
Fight or flight, Diana told herself. And flight is not an option. I need to fight. Please, alien ancestors, let me fight.
She was, despite the fear clouding her head, vaguely aware of her ancestors granting her request. As she'd suggested (or perhaps subconsciously suspected) before this nonsense began, the ground under her feet turned slippery, coated with something hard, slick, and thick enough to not break under her weight.
And, Rotom noticed, it wasn't fireproof. The only place safe from the slippery substance was a large circle around Eli's feet.
"Hello, traumatic superpower awakening," she mumbled, not once taking her eyes off of the UB. "I was hoping I wouldn't have to encounter this trope."
Rotom, being less digestable than the kids, turned on the camera to record the fight and to get information. The beast, it seemed, was reading Diana's new gift as hostility, and seemed to be reluctant to get closer.
Could whatever it was be weak to ice?
The beast was quick to realize that Diana was not the only Faller in the cave. Eli, much faster due to years of living in fear and paranoia, realized this fact at the same time, and grabbed Diana by the wrist, melting whatever it was Diana's fright had generated as he made contact with it and tracking wet shoe prints as they retreated to the bottom of the cave, Rotom flying along behind.
"Ok," he said, as Diana attempted to shake her fear away, "I think it's safe to say it doesn't like you."
"Likely a power surge that repulsed it," Rotom answered at once. "It's pretty clearly a Dark-type, but if its secondary type is weak to Ice, it would explain why it ignored Diana. It read her fear as hostility. It read her as an Ultra Beast."
"Weak to Ice, huh?" Eli felt his own internal furnace turn down at the thought, down to a mere rush of warmth in the face and chest. "Well, that's good news. I don't want to see it again, but if we know what it's weak to, and have something on us that can take it..."
"You're going to fight that thing?" Diana yelped. "Eli, don't be stupid! You can't win! You and Ninetales and Snorunt will all be eaten alive - literally!"
"Diana." His hands were shaking, but he placed them on her shoulders to pretend otherwise. "You just did something that you've never done before. I've been the Human Torch for as long as I can remember, but you've been Elsa for two minutes. I know how to weaponize fear, you know how to battle. Let's try each other's roles for a bit."
"You've never lit yourself on fire," Diana said quietly, and Eli shook his head.
"I've never done a lot of things," he said. "I've never taken the island challenge. I never beat you in battle. Until you got here, I'd never gone more than six hours without my powers acting up. I never got a Z-ring, I never even got a real important battle on our journey! The only heroic things I've done were stealing from bad guys and trying not to die. But I refuse to believe that I helped save the world multiple times just to end up sliding down the gullet of a creature from another dimension!"
Diana still wasn't sure, but any attempt at raising an objection was drowned out by a loud crash as the beast finally slipped on the wrong part of the path, and it slid penguin-style into the hole the kids were hiding in.
It got stuck in the entrance. This was not as amusing as it should have been, but even though the rocks burst into flame and the drops from the leaky ceiling shattered when they hit the ground, Eli took a stand in front of the trapped beast.
"Rotom," he said, voice shaky but determined. "Play boss music!"
The beast quickly realized that facing Eli was a horrible idea.
It didn't have any reaction to the fire at all, but it did not react well to Ninetales. Eli took a moment of sadistic pleasure from it, before giving the official command.
"Ice Beam!"
Ninetales didn't have to aim the attack, as the beast was still stuck in the entryway. And it was easy for her to avoid the attack with the monster stuck, even as its tongue arms thrashed around in what was, actually, a Thrash attack.
It was almost an anticlimax when Eli caught it in the third Beast Ball he threw. Ninetales definitely looked disappointed.
Diana was just grateful it was gone, as her relieved laughter echoed in the cave. "I...wow." She coughed a bit, and Rotom was the one who dove in to grab the duct tape. As soon as Eli handed her the ball, she wrapped this one in seven layers instead of one, an 'honor' shared only by the Nihilego. Her hands were still shaking, and Ninetales went around putting out all fires with melted Ice Beam attacks. "I did not actually think that...that I could scare off a UB like that."
Then her laughter turned to crying, and she flew to Eli, hugging him both in relief that he was still alive and in an attempt to warm herself. He responded with the usual awkwardness of a preteen being hugged by a relative, patting her on the back and saying the sound effect out loud, making her choke out a giggle.
"Sorry about the awkward family hug," she mumbled. She didn't let go - the cold was still there, and she was afraid she might do what he was known to do if she was free. He understood.
Rotom, eventually, called their attention back to the discarded Beast Ball. "So," he said, and Diana finally trusted herself to pull herself out of the hug. "Are we going back to Looker now, or...?"
"We should," Diana admitted. "And maybe we should turn this thing on him. Give him a little scare for putting kids in danger."
"No," Rotom said immediately.
"Yes," Eli said at the same time.
Diana laughed and patted Rotom on the head. "Sorry, pal. You got outvoted."
When they returned to Looker to inform him of their success, Anabel had returned. Looker confiscated the new Beast Ball immediately, and Diana turned to leave.
"Aren't you going to take Guzzlord with you?" Anabel asked.
"You named it Guzzlord?" Eli asked in return.
"It does like to eat," Looker said, as if that explained anything. "And speaking of eating! Our mission is complete, which means that it is time for a feast!"
"Wrong," Diana said bluntly, looking the man in the eye. "It means that the three of us - " she gestured to Eli and Rotom, "- are going on vacation. I'm not going to battle, I'm not going to do science, I'm not going to do anything except maybe see how many books I can read in one day."
Rotom made a surprised whirring sound. "You're not going to do science? Who are you and what have you done with Diana?"
"I'm not going to work for the professor," she corrected, to her mechanical friend's relief.
Anabel, at least, seemed to understand. "Then I will call Gladion and Wicke at Aether Paradise," she decided. "They provided the Beast Balls, after all. They should join us."
No one had any objections to that. There were no more Ultra Beasts to catch. They could start that well-earned vacation tomorrow.