Author's Note: Hey there. I decided to do a Spooktober writing challenge. 31 days, 31 prompts. I just googled Spooktober prompts and got the ones I'm using. Hopefully one will be written everyday but you never know. I think I'll try to update every few days so it'll probably stretch into November.

This is my first Ben 10 fic. I've been having some writer's block so I wanted to write a new idea and I realized I've never written one so I felt like it was time to write a Ben 10 story after being a fan since I was ten.

Note: I intended for this to take place after Omniverse but the timeline isn't really important. Could be any time.

Prompt 1: Trick

"Ben?"

"Yes?"

"What is this?"

Far beneath the streets of Bellwood, two figures walked the streets. One was distinctly human and the other… wasn't. If they were on the surface, any human would have fled at the alien's tall, lanky build and orange eyes as sharp as his teeth. Down there, the only odd looks Rook received were due to his partner's fame.

The pair had tagged along to one of Grandpa Max's numerous trips to Undertown to find whatever alien food he wanted to toss into the kitchen tonight. Max had disappeared maybe an hour ago, leaving Rook and Ben to their own devices. Predictably, Ben wanted to wander. Rook normally would've been annoyed but if not for Ben's aimlessness, he never would've found this… orange thing.

"That's a Jack O' Lantern," Ben told him, coming to a stop in front of the house Rook had found the Jack O' Lantern. "People carve out pumpkins and put faces on them and put little candles in them to light them up."

Rook lifted the gourd up and peered into one of the holes in it. They vaguely resembled a face but Rook wouldn't have noticed if Ben hadn't mentioned it. He had never met a creature with triangular eyes or a mouth like this one. "Why? Is it some kind of dwelling for smaller alien species?"

"What? No," Ben said. He took it from Rook's hands and put it back down on the bricks that made up the steps leading to the house. "It's an Earth thing thing. I think they're for scaring away spirits or something like that."

"Really? If they were for scaring spirits, I would imagine that I would have seen one already. Are they common relics?"

"You usually only see them around…" Ben trailed off and stiffened.

Rook frowned, picking up on Ben's reaction and tensing. "Around what? Is it dangerous?"

"Only to us," Ben said. Nervously, he glanced around and further alarmed his Plumber partner. "Grandpa goes all out on Halloween."

"Halloween?" Rook repeated. His face suddenly melted into a grin. "Oh! I read about that in my Earth studies. It is an Earth holiday on the 31st of October, is it not? Today is only the first of the month. You have nothing to worry about. I'm sure Magister Tennyson-"

"Dude, you haven't been on Earth long enough to know how humans get about holidays," Ben said. He glanced around the street. They had wandered into a residential area, something they rarely did. The two usually just stuck to the shops on the main strip. Unless they were chasing someone, of course. Rook worried that they were lost for a split second but Ben took off running before he could think about it much.

Ben, being human, was much slower than the Revonnahgander so Rook barely had to jog to catch up with him. Ben barely spared him a glance and just kept running.

When they returned to the main strip, Ben skidded to a halt and began looking around frantically. Not understanding his actions but taking pity on his partner, Rook grabbed him by the back of the hoodie and pulled him behind the sock store.

The alien shopkeeper didn't seem to care but Rook made sure not to touch anything as the two hit the floor. He pulled himself together quickly and frantically gripped Ben's arm. "Why are we running? Did you see something?"

"Dude," Ben said, sitting up to put his hands on either of his partner's shoulders. "Halloween."

"Yes," Rook repeated, slowing his voice as if humoring a child. "Halloween."

"Halloween is like the worst holiday!" Ben said, throwing his hands up in the air dramatically.

"Why?" Rook asked, tilting his head curiously. "I was under the impression that human adolescents enjoy the holiday."

"Well most human adolescents don't have a grandpa like Grandpa Max."

"I do not follow," Rook said. From his experience with the magister, Max seemed like a fantastic grandfather.

"You ever see those old horror movies?" Ben asked. Rook shook his head. Ben facepalmed. "Duh. Of course you haven't. Well, they're terrifying. The stuff Grandpa does is straight out of one of those. Plus crime rates go up."

"You usually enjoy high crime rates," Rook pointed out, "even though you really should not."

"Beating up bad guys is not fun when they have blood painted dripping from their mouths and weird bruises drawn on them! Especially if everyone who is not committing a crime is dressed the same way. It gets real confusing."

"There you boys are," a voice suddenly said. Rook looked up to see Max leaning over the counter of the sock shop. The shopkeeper was waving a sock in his face but Max didn't care. "Sorry it took me so long to find where they sell ewekansige vreemde woord eel eyes. Now I just need to find something I can serve them on."

The heavy set man gave a wide smile as he held out a hand. In it was a bag of green eyes with purple veins trailing out from them. They wrapped around the edges of the bag like they were trying to crawl out. Some of them still had parts of the eye socket attached.

Ben's face looked less than enthusiastic. Even Rook's stomach dropped and he usually liked the kind of stuff Max cooked. Ben and Rook peeled themselves off the floor of the sock stand and followed Max back onto the streets.

"See?" Ben whispered quietly, leaning into the taller boy. "Ewe-za-whatchamahoozit eel eyes!"

"You are speaking like you are trying to make a point but I do not see what the point is," Rook told him. He doubted he would ever learn to understand humans. Especially if that human was Ben.

"Eyes! Halloween stuff! He's so about to do something."

"Ben. You are being paranoid," Rook told him. "It is only the first of the month. If he's going to do anything-"

"He's going to start now," Ben interrupted. "We have to hide."

"Ben-"

"Do you want to eat eyes?"

Rook paused. "Good point."

"Hey, you two, let me know if you see any Methanosian skulls," Max said, turning around. Ben and Rook's eyes widened but Max wasn't alarmed in the slightest. "I think the fumes that get trapped inside will go well with the ewekansige vreemde woord eel eyes. I hear the gas seeps into the flesh of the fruit and tastes fantastic. I think it will compliment the juices in the eel eyes pretty nicely."

"Methanosian?" Rook repeated. He wanted to gag. That sounded disgusting. Few had much experience with them but whenever Ben transformed into one, the smell clung to his fur for days and lingered even after he bathed. In fact, water seemed to make it worse.

"Like Swampfire?" Ben questioned. He looked horrified. Any talk of eating one of his aliens usually triggered some kind of reaction and never a good one. He clutched his stomach and looked like he was going to vomit.

"Oh, don't worry. They grow back, no harm to the Methanosians."

Rook and Ben stared at each other. Green eyes met orange, neither wavering as they silently exchanged words that couldn't be conveyed clearer if they were speaking. Then, without even a glance at Max, they bolted down the long concrete path and made a beeline for the exit. After the Proto-Truk and the Tenn Speed were destroyed followed by the Time Cycles, they relied on others for transportation and neither was about to run back to the Plumber truck Max had taken to drive them here. They would take the surface streets and get lost trying to escape if they had to.

"Run. Run. Run. Run," Ben chanted as the two sprinted through the streets. He nearly crashed into the rabbit-like alien selling tentacles on a stick, making the alien stumble to the ground. The alien began shouting at him but Ben and Rook were long gone by the time he was back on his feet. "Sorry!"

Ben pumped more energy into his legs, getting in front of Rook for a few seconds. He had to swerve to avoid tripping over a small Atrocian child who was crossing the road with his mother. Ben ended up stumbling.

Rook caught him before he hit concrete and began running with the human under his armored arm, much to Ben's annoyance. "Hey!"

"This is faster," Rook told him. It was true, Ben couldn't deny it. Rook was tall even for a Revonnahgander so his strides were longer and his training kept him in better shape. Ben looked like a twig beside a powerful oak trunk when he stood next to his partner.

Of course, Ben's personality more than made up for it. What he lacked, he made up in volume, rashness, unpredictability, and poor decisions in general.

Case in point, now.

"I'll show you faster," Ben said, slamming the Omnitrix.

Rook felt the weight in his arm increase and the shape meld into another. XLR8 dropped from his grip, wheeled feet hitting the ground, and tossed him over his shoulder before zipping away.

"This is most unflattering," Rook said as he tried to get into a better position. XLR8's shoulder bone was digging into his stomach. He could feel it even through his proto armor. That combined with moving backwards made Rook feel a bit more sick than he had a moment ago.

"Dude, being carried like a sack of flour is better than being carried like a football," XLR8 said, voice somewhat obstructed by his mask.

"I can't see like this. What if there is danger?" Rook asked as he twisted his torso around so he was more upright.

"There won't be any-"

"Look out!"

At the warning, XLR8 slammed on the breaks but it wasn't enough to keep the two from skidding into the energy net laid out on the concrete. The second his foot hit the edge, it flew into the air and enveloped them. XLR8 hissed as the energy hit his arm and curled himself around his partner to shield him slightly even though Rook didn't need the protection. His armor was more than enough to save his fur from being singed. Having Ben on top of him on the other hand...

Rook hated nets. Being suddenly thrown from a standing position to an awkwardly suspended one was very uncomfortable. Especially if there was another person in the net with him. There was far too much contract and armor against… whatever XLR8's body was made of was far from a good feeling, not to mention their different biologies. "Ben. Remove you tail from my-"

The Omnitrix beeped and XLR8 timed out, leaving Ben in his place. Rook shifted so he didn't crush him now that their roles were reversed.

"Thank you."

Ben rubbed his tail bone, shaking the net slightly. Rook felt human skin rub against his fur. It was a strange feeling, one he doubted he could get used to. "Remind me to turn into Fasttrack more often. He doesn't have a tail."

"He has a harder time stopping. At least with XLR8, we had some hope of avoiding this trap."

"Dude," Ben said. "Have you met my grandpa? There's no escaping his traps. He's magic or something."

"You think this was Magister Tennyson?" Rook questioned, surprised.

"Who else could it be?"

"Zombozo, Fistrik, Eighteight, Sevenseven, Inspector 13, Vulkanus, Liam, Corvo, Psyphon… Anyone really. Undertown has a very active criminal population."

"But in October?" Ben argued.

Rook shifted so his spine was curved against the natural bend of the net's mesh nicely. "I don't think they care what month it is."

"But Grandpa Max does!"

"Ben…"

"I can't take my eyes off you two for one minute," a familiar voice said.

"Magister Tennyson!" Rook craned his neck to look over his shoulder to look at the older man. He couldn't quite turn around enough but the brightness of Max's Hawaiian shirt stood out even in his peripheral vision. "Ben thinks that you are trying to… Actually, I do not know what he is accusing you of but please prove him wrong and cut us free."

"Oh, I can't do that," Max said.

Rook blinked. Max's tone was even, confidant. Just from his voice, it was clear that he could in fact do what Rook was asking him to do but was choosing not to. That Rook could not understand. "Why?"

"Isn't it obvious?" Ben groaned, burying his face in his hands. "We passed up on the 'treat' so we're getting the trick."

"What?"

"That's right," Max said, walking forward. He reached into the bag of eyes and pulled out a fistful. He held it up to Rook's face like an offering and raised his eyebrows. The veins reached out and wriggled in the air. A putrid smell hit Rook's nose. His nose wrinkled in distaste. Rook grimaced and pulled his face back. Max smiled. "Last chance."

"Pass," Ben and Rook said in unison.

"Then I hope you'll love what I have in store for you boys this year," Max said. He drew his stun gun and suddenly the world went dark.

Author's Note: Good start? Bad start? I've never written something like this and I'm definitely going to have a hard time. I've never written horror either so chances are it will be more light hearted and slowly become more serious. Or it'll all be like this. I don't know. I've read a couple of good horror stories on this site but I don't think this compares. I'll do my best. I'll probably do some editing at some point.

Edited 10/1/2020