Author's Note: Hello, everybody! I'm back, and it didn't take me nearly as long as it usually does! Yay! I even made it by the deadline I had set! Double yay! I actually would've had this up sooner, but I really hated a lot of my phrasing in this particular chapter. So, after plenty of editing, I ended up with something that I feel like is worthy of being read. With that being said, I hope that you feel the same way I do. I hope you enjoy chapter ten!

This hallway was much shorter than the previous one, only a few feet separating one door from the other. It made the pair feel uneasy, like there wasn't enough time to prepare for what was coming next.

Without hesitating, Luigi threw open the door at the end of the hall, praying that his brother would be behind this one. Instead, he found a massive room with cells lining the walls, more Petalburg residents trapped behind them. Strangely enough, they didn't seem to be possessed by Boos.

"Koops!" A female voice shrieked.

"Koopie Koo?!" Returned Koops. Once he saw her, he was running towards her, only to be stopped by a sharp grip on his arm. He glared at the plumber holding him back with annoyance.

"Koops, don't." Luigi pleaded. "Something's not right here."

As if on cue, a choir of eerie laughter echoed off the walls. A hoard of Boos appeared in the center of the room, their numbers greatly overwhelming. Luigi was sure that there had to be at least fifty of them.

"You think you can beat us?!" One cackled.

"With our combined forces, not even that stupid vacuum can stop us!" Another chimed in.

The group of Boos began to fly in a circle, creating what looked like a tornado of ghosts. Luigi tried his best to watch their movements through the insane wind they were creating, while his koopa counterpart was trying his best to look away. Luigi's eyes watered against the wind, causing the mass of Boos to blur together.

The plumber's eyes widened in horror when he realized they weren't just blurring together.

They were literally combining into a massive Boo.

Once all the Boos had fused together, the figure grinned down at the two.

"Are you ready for Boolossus 2.0?!"

"Luigi!" Koops screamed, pulling him out of his trance-like state, but the koopa's warning came too late. Boolossus rammed into the tiny plumber, knocking him into the stone wall of the room. Pain blossomed throughout his body, but he tried to focus nonetheless. His current state of vision made that difficult, though, as he was seeing doubles. A throb at the back of his head had Luigi reaching up to touch it. Upon contact, he could feel the sticky warmth soak into the fabric of his glove. He brought his hand up to his face afterwards, and the sight of crimson nearly made him vomit. He never was all that great with blood.

"Had enough yet?" Boolossus bellowed.

With what strength he could muster, the plumber stood on legs that didn't seem to want to work. Koops was at his side trying to assist him, but Luigi waved him off. He carefully readied the Poltergust at his foe.

Boolossus smirked. "Do you really think that's going to do anything while we're like this?"

Luigi lowered the Poltergust in defeat, trying to craft a plan in his aching head. He didn't have much time to think, though, as Boolossus came bouncing towards them. Luigi and Koops jumped to either sides of the enemy as he came crashing into the wall with seemingly zero damage. The plumber shakily stood once more, bracing himself against the stone wall, when suddenly it hit him. This wasn't the first time he'd fought Boolossus, and the solution right in front of his face.

"Koops!" Luigi yelled from the other side of the enemy. "Use the knife!"

Boolossus gave a hefty laugh at that. "Do you really think that a mortal weapon will have any effect on me?! I'd like to see you try!"

Without any hesitation, Koops lunged at the combination of Boos, driving his knife into them. Boolossus popped like a balloon, scattering out across the room. Luigi made quick work, sucking them into his vacuum with decent enough aim. He managed to catch several before they combined again.

Boolossus was visibly disturbed at how a powerful being such as itself could be bested by the two of them. Then, it zeroed in on Luigi.

"They can't win if there's only one of them, right?!" The ghosts cackled nervously. Suddenly, they charged at the plumber, who barely missed them with a well timed duck.

Luigi turned to face them, but the dizziness clouding his brain caused him to fall on his rear. A blur of colors, which he quickly identified as his partner, jumped over him, stabbing the oversized ghost in the back. The plumber stared for a moment before realizing that this was his cue. He gripped the Poltergust, sucking in several more Boos than last time. When Boolossus formed for the third time, it was significantly smaller than the first. While definitely smaller, this only made the Boos more agile, and they wasted no time plowing into Luigi for the second time.

The plumber rolled across the floor, the stone underneath him ripping his clothes and scraping at his skin. He stopped on his back, wearily staring at the ceiling. He heard the pop again, and as much as he struggled, he just couldn't find his footing. After several seconds, Koops was by his side.

"Luigi?!" The koopa yelled, but everything sounded so muffled to the green clad man. It was like trying to listen to someone talk underwater. He eventually found hands pulling at him in an attempt to force him to his feet. With an arm draped over his friend's shoulder, and his friend clutching at his side, he finally did stand, distantly looking forward towards Boolossus.

Koops' grip tightened on the plumber as he spoke. "Luigi, I need you to focus! Please! I-I can't do this without you!"

Without warning, Luigi found himself on the floor again, although in no more pain than before. He lifted his head to see where he and Koops were standing, only to find Koops in a much similar situation to his own. He was on his back, and his shell was preventing him from getting up. Boolossus was lingering dangerous close to Koops, though, and seeing his friend in danger forced Luigi to his feet.

Although the throbbing in his head protested, Luigi yelled at the Boos. "Hey! Get back over here! I'm not finished with you yet!"

Boolossus turned to look at the plumber, and deciding that it would be more fun to end the man who had given them hell all those years ago, advanced towards Luigi instead. Luigi stood his ground, hands gripped tightly on his Poltergust even though it would do him no good like this.

Just as Luigi was sure he was going to be slammed into once more, he heard a pop, and Boos scattered all around him. He didn't hesitate this time. Before they could fuse again, all of the remaining Boos had been successfully captured. Relief washed over the plumber, and his body gave out just as the cell doors opened.

XXXX

When Luigi finally came to, he grimaced at the way Koops was screaming in his face. "I-I'm awake!" He finally yelled back.

The choir of cheering did nothing to help his headache, but it did make him suddenly aware of all the people circled around him.

"W-what?" Luigi stammered out.

"We did it, Luigi!" Koops finally confirmed. "We beat Boolossus! All the cells opened afterwards, like magic!"

Luigi gave a smile and tried to stand, but a firm hand pushed him back to the ground.

"That's probably not such a good idea." Came a female voice. "You're really hurt. You should rest for a minute."

Luigi looked up at the koopa talking to him, recognizing her as Koops' girlfriend. Shaking his head, he attempted to stand once more, Koops helping him to his feet this time.

Koopie Koo crossed her arms, sulking. "Fine. Ignore me. Stubborn man…"

"I've got to continue." Luigi said to no one in particular. "I've got to save Mario."

Koops nodded in understanding before a sparkle on the ground caught his eye. Right where the nozzle on the Poltergust had been, laid a black, metal key. He quickly snatched it up, showing it to the plumber.

"Look, Luigi!" The koopa exclaimed. "I think this is the key to that last door!"

Luigi gingerly took the key from his friend's hand, sticking it in his pocket. "C'mon." He said. "We don't have any time to waste."

XXXX

The foyer was a heartwarming scene. Families that had been separated for who knows how long finally reunited. It was bittersweet for Luigi. Mario was still missing.

As everyone was having their little family reunions, including Koops with Koopley and Koopie Koo, Luigi snuck over to the only unexplored door. It's appearance seemed more ominous than the other doors, coated in black rather than brown, and unlike the others, this particular door had a small, barred window at the top. Looking into it didn't do much good, as it seemed like only a endless descending stairwell lined with torches awaited behind it.

As carefully and quietly as he could, Luigi stuck the key into the lock, slowly unlocking the door. He pushed the door opened with a not-so-quiet creak, and made quick work of slamming the door behind him once inside. He jammed the key back in, locking the door barely seconds before he saw Koops' face behind the bars.

"What are you doing?!" The koopa yelled, drawing much unwanted attention.

"I can't ask you to come any further." Luigi simply stated, his gaze intense. "You've got what you came here for."

Koops gripped the bars on the window tightly. "We were supposed to be in this together!"

"Koops," Luigi started, "I couldn't have asked for anyone better to accompany me on this journey. But I can't let you come any farther. It's too dangerous, and I wouldn't forgive myself if anything were to happen to you. Besides, I think you need to stay here with everyone. Make sure they stay safe." Clearly seeing the doubt on Koops' face, he gave his friend a smile. "Believe in me, Koops. I can do this."

The koopa sighed in defeat, giving Luigi an understanding nod. "I believe in you." He stuck the sheathed dagger through the bars, allowing Luigi to take it from his grasps. "I wish you luck finding Mario."

Luigi smiled and offered nothing more, descending the steps until he was no longer in view.