KC: Nya, another cross-over~! Yay~! And, yes, I did change my name. I figured that I should so that it would be easier to remember, since I'm Kenny-chan on all of the other writing websites I'm a part of. Anywho, I absolutely fell in love with Train when I first saw him. I was like, "You are so adorable! I don't think it's even possible for you to get any cuter!" Then, when I was thinking about KHR!, an idea popped into my head. I thought, "Hm, what would happen if I made a cross-over for this?" Thus, this story was born! I'm proud of myself for writing this, so please by nice! Also, there's a brief reference to a story that LinChungIsHot wrote.

Disclaimer: I do not own Black Cat, Katekyo Hitman Reborn!, or any characters. I own Nikki, and LugiaSoul owns Obsidian.

"I found a new bounty!"

All heads turned to stare at Train, who was grinning at the gathered people.

Eve peeked at the cat-like man over her book and asked the question that everyone was thinking. "Who is it?"

Train held up the paper in his hand, and Nikki's heart just about stopped. "It's the tenth generation Vongola boss," he replied.

Nikki's brown eyes remained glued to the paper, and Obsidian glanced at her questioningly. "Is something wrong, Nikki?" the black-haired girl asked.

Nikki then realized that all eyes were on her. She looked away, embarrassed by the attention, and replied, "No, I'm alright."

Eve stared at her, trying to figure out why the older woman was lying. She was good at it, but Eve could still tell; she and Nikki just understood each other like that.

Eve also noticed the way that Nikki's blush deepened when Train put his face up close to hers. It was funny in a way, because Train and Nikki were dating, and they were obviously in love. There had been an incident before where an assassin that also loved Train had attacked Nikki and put her in the hospital. Nikki had been almost dead when she had been found, and Train had run off to try to get back at the assassin. Nikki had woken up in the hospital bed and began shouting about how someone needed to find Train.

Train's location was pinpointed, but when he was found, the assassin that had injured Nikki was holding a knife to Train's throat. She had threatened to kill him if anyone stepped closer to them, but Obsidian, a sweeper that Nikki treated like a sister, told her that that was a bluff, that she wouldn't kill the man she loved.

The assassin had released Train and jumped out the window, and Train had said that the girl's name was Katrina, although she preferred to be called Bobby.

The group of sweepers didn't heard from the girl again.

Now, for some reason, Nikki seemed to be affected by the fact that she had to capture the tenth Vongola boss. Was it someone she knew from before she had run away? Eve voiced her question, and Nikki looked at her, obviously surprised that the younger girl had asked.

After a few moments of silence, Nikki admitted, "Yes, he's someone from my past."

"He wasn't an old boyfriend, was he?" Train had always been protective of Nikki, especially after that horrible breakdown she had had and the incident when Bobby had attacked her and nearly killed her. But the thought of Nikki being with someone else obviously made him angry, and Eve was surprised by his possessiveness.

Nikki shook her head, a small smile on her pink lips. Train felt the urge to kiss those lips, just to let her know that she was his, but he didn't want to do that in front of everyone. Besides, there would be plenty of time for kissing later. "No, Train," she laughed. "He's just an old friend from middle school."

Nikki's answer made Train happy, and he couldn't stop a smile. Good, he thought. She never belonged to anyone else.

Nikki must have read Train's mind, because she grinned and said, "It doesn't matter, anyways. I belong to you and only you."

Train blushed at the comment but smiled. Nikki was sweet, even if she was a bit dense sometimes. Train's smile slipped; there was still a problem. "Nikki, was this guy a close friend of yours?" he wondered.

Nikki studied the poster again and replied, "Yeah. He and I were close."

"You don't have to –" Sven started.

Nikki held up a hand to stop him. "No, no. I'm part of this team, and I'm going to take part in any bounty hunting that we do." The look in Nikki's brown eyes told them that she was going to find a way to go even if they tied her to a bed.

Sven sighed, giving in. "Fine. You'll come along."

Although Nikki tried to hide it, everyone knew just how much this was going to kill her, and Train hated himself for allowing her to come along. He had promised that he would never let anything happen to her because he loved her, just like he loved Saya, and he didn't want to lose Nikki like he had lost her.

A few hours later, Train, Nikki, Sven, Eve, and Obsidian were standing outside of the building that Tsuna was supposedly in. Nikki's hold on her gun tightened, and Obsidian shot her a worried look. Nikki shook her head and forced a smile. After taking a deep breath, she said, "Let's do this."

Nikki cautiously looked around the corner. When she saw that no one was coming, she gestured to her friends, telling them to follow her.

After some time, the group stood outside of a door. Nikki turned to look at her friends, and she put her gun away. "Okay," she began. "This is my plan. Tsuna knows me. If I go in, he won't suspect anything. Once I've got him convinced that it's still OK to trust me, I'll ask him to take a walk with me. If he says yes, I'll lead him out here, and you guys'll take him. If he says no, I'll take out my gun and tell him to come with me, or I'll shoot. Do not, and I repeat, do not come into that room. The only time you are allowed to come in there is if I'm in danger."

"How will we know if you're in danger?" Obsidian asked, causing Train to stiffen.

"Nikki, you are not going in there alone," Train told her.

Nikki looked at Train, startled. "What do you—" Train cut her off.

"I promised you that I wouldn't let you get hurt again, that I would protect you," Train responded. "If I let you go in there alone, then I can't guarantee that I'll get to you in time if you're in danger." Train's voice almost cracked; he couldn't stand the thought of losing someone so important to him again, not after losing his parents and Saya.

Nikki sighed and hugged Train, and he instinctively hugged her back. "I'm not gonna get hurt, okay?" she mumbled into his shoulder. "I'll be fine." When Train started to protest, her hold tightened, silencing him. "If you're really that worried," she said, "then Eve and Obsidian can come in with me."

"Why can't I come in with you?" Train wondered. "I'm your boyfriend." He paused. "I love you."

Train felt Nikki smile against his shoulder. "Because Tsuna knows who you are: the Black Cat that turned into a bounty hunter. If he sees you, he'll know something's up. I can't risk putting you in danger."

It was funny how she was worried about what he had been earlier.

Nikki pulled back slightly and kissed him. Train immediately kissed back and nibbled slightly on her bottom lip. Nikki pulled away, and Train pouted. Nikki grinned and pulled out of his arms, poking him on the nose and saying, "You can get another kiss later."

Nikki turned serious and looked at her friends. After taking a deep breath, she told her partners to hide, and once they were hidden, she knocked on the door, not even prepared for what was about to happen to her.

Gokudera was talking with Tsuna when they heard someone knock on the door. When Gokudera answered it, already prepared to protect Tsuna he was shocked to see an old friend of his standing in the doorway with her hand still raised from knocking on the door.

Gokudera gasped. The girl hadn't changed much; her brown hair was still pulled back in a ponytail, her brown eyes were still warm and were still the color of chocolate, and he noticed that there some freckles sprinkled across her nose. She was definitely taller, and her chest had grown (not that he was looking there or anything).

Nikki.

"Nikki," Gokudera said. "I haven't seen you since we graduated from high school."

Nikki was obviously shocked to see Gokudera there, but she smiled anyway. "Yeah," she agreed. "I've just been…busy lately." She looked around Gokudera and smiled at Tsuna. "May I come in?" she asked.

Gokudera stepped aside and let Nikki in.

Nikki walked up to Tsuna, and he stood to hug her. "How've you been, Nikki?" Tsuna asked.

"Good," Nikki replied. "And you?"

Tsuna shrugged. "Good."

"That's nice to hear," Nikki stated.

Tsuna spotted something on Nikki's left ring finger and picked up her hand, examining the object. It was silver, and it had cat designs on it. "What's this?" Tsuna wondered.

Nikki blushed and hesitated before replying, "It's a ring, obviously."

"Who gave it to you?"

The room was silent after Tsuna asked that question, and Gokudera looked at the ring as well.

"It…it's from my boyfriend," Nikki admitted.

Gokudera stiffened, but Tsuna questioned, "Who's your boyfriend?"

Nikki looked away before leaning over the desk that separated her and Tsuna. She whispered, "I don't wanna say that in front of Gokudera. You know how jealous he can get."

Tsuna nodded in agreement.

"However, I can tell you who he is if you take a walk with me," Nikki offered.

Tsuna stood up and told Gokudera that they were going for a walk.

"I'll come with—" Gokudera was cut off by Nikki.

"No!" she protested. She blushed and looked away when Gokudera and Tsuna looked at her. "I mean, I wanna talk to Tsuna alone," she said.

"I still think—"

"It's alright, Gokudera," Tsuna assured him. "We're just going for a walk." After Gokudera agreed to let the two adults take a walk, Tsuna smiled and said, "Let's go."

Nikki's heart clenched when she saw that look of trust in Tsuna's eyes. It hurt to know that she was about to betray him, and when she turned to look at Gokudera to tell him good-bye, the words stopped on her lips. Gokudera was looking her with adoration and trust, and Nikki realized that Gokudera loved her.

Nikki looked away, not being able to look at him, and walked out the door with Tsuna. When they got outside, Nikki shouted, "Now!"

Sven, Eve, Train, and Obsidian all leapt out of their hiding spots at once, and Tsuna stared at Nikki, dumbfounded.

Nikki looked away and said, "I'm sorry, Tsuna."

"You work with the Black Cat?" Tsuna exclaimed. "I hope you realize that he can kill you!"

"Train wouldn't hurt me!" Nikki snapped, feeling hurt that someone would even suggest that Train would hurt her; that was just insane. Nikki knew that Train loved her and that he would do anything to keep her safe.

Gokudera threw the door open. "Tenth! Nikki! What's-?" Gokudera stopped when he spotted the four people in front of Tsuna and Nikki, prepared to capture Tsuna. "What do you want?" Gokudera asked, stepping in front of Nikki and Tsuna. "I'm not going to let you hurt boss or Nikki!"

"Gokudera!" Nikki exclaimed. "Stop! Those are my partners!"

Gokudera stopped dead in his tracks and turned slowly to look at Nikki. "What?" he said. "You're partners with the Black Cat? Partners with a killer?"

Nikki gritted her teeth and said, "He's not the Black Cat anymore, and he's not a killer!"

Gokudera scoffed. "Of course he is! Do you know how many people he's killed?"

Nikki pulled out her gun and pointed it at Gokudera as he began to advance on her partners. "Take one more step," she threatened, "and I'll shoot."

"Go ahead," Gokudera dared her. "I don't care. You betrayed me."

Nikki pointed the gun at Tsuna. "I'll shoot Tsuna."

That stopped Gokudera. "Don't."

"Then leave my partners alone," Nikki commanded.

Gokudera didn't move as Nikki grasped Tsuna's elbow and began to walk towards her partners, holding the gun to Tsuna's head the entire time. "Don't move, Gokudera," Nikki warned.

When Nikki got to her partners, Gokudera began to run towards them.

Nikki took the gun away from Tsuna's head and fired at Gokudera.

The bullet made contact with Gokudera's shoulder, and he fell to the floor, crying out in pain.

Nikki and her partners began to run through the hallways, leaving Gokudera behind and running ahead with Tsuna.

Nikki almost stopped when she heard Gokudera call, "Whether I live or die, I'll never forgive you!"

Nikki knew that she should've been pained by his words, because if she had said that to him, he would've been pained.

Because Hayato Gokudera loved her; that's why he would have been pained.

But Nikki Albrite loved someone else; she loved Train Heartnet.

KC: Whoo, six pages! This took forever! I started writing this at 1:00 a.m. and stopped at 2:46 a.m. That's almost two hours. -3- You people are lucky I love you. Anyways, I hoped you enjoyed! And hopefully no one was (too) out of character. Anyways, good-night!