Okay, so, this one may be a long time coming, but I'm sure that many of you may be excited to know of a new franchise that I am attempting a crossover with.

Specifically, That Time I Got Reincarnated as a Slime.

Even if this particular story falls through, I have a few ideas. Hopefully, you'll enjoy this one...

UNLIKELY FRIENDS

CHAPTER 1:

THE FUGITIVE

The shaft of light penetrated the darkness, searing the eyes of the prisoner. A pained hiss escaped the prisoner's lips, before a robed form entered the cell. After a moment, the prisoner asked, "What do you want?"

"…Your rudeness is forgivable. Unlike the other three, you seemed to be tractable, at first. Having you under the locking curse and then imprisoned was a matter of prudency more than anything else. However, when your Unique Skill kept manifesting…it's rather terrifying, to manifest such things, such nightmares."

"About the only thing this prison had better than the one I was in back home was the lack of soul-sucking demons," the prisoner said. "If you really were sorry, you'd let me go. Instead, you kept me in this shithole for over a year, and those three wankers come here to taunt me every so often."

"You are a weapon of Falmuth, boy. You are needed for our defence…but I feel that your talents have gone to waste. I will remedy that."

"By brainwashing me?"

"Nothing so pedestrian. Don't worry. You'll be at peace soon."

The prisoner realised something was up when the older man began approaching, and then, he laughed. "What's so funny?" his visitor asked.

The prisoner smirked, before removing his hands from the shackles keeping him there. "Impossible. The locking curse on you…"

"I heard you were coming, and panicked, trying everything I could. And then, I remembered a spell that could be used on that. Finite Incantateum." With a wave of his arm, the door shut in the darkness. "Now, I'm not locked up in here with you. You're locked up in here with me." Emerald eyes glowed in the darkness. "Unique Skill: NIGHTMARE EDEN(1)!"

"So, what's the problem?" Rimuru Tempest asked. The high-pitched, childish and androgynous voice belied the fact that he was once a 37-year-old Japanese salaryman and otaku by the name of Satoru Mikami. Now, after a mugging gone wrong, he died, and somehow reincarnated in a fantasy world as a slime monster. He'd just returned from the Dwargon Kingdom after a series of mishaps there, only to find the Goblin Chief, whom he had Named Rigurd, asking for him.

"…Yesterday, a human somehow entered the village, Lord Rimuru. He suddenly appeared, as if through some kind of teleportation magic," Rigurd said. "Made a noise like a whipcrack in the process. Given your rules about humans, we're keeping him here for now, but I thought you could make the decision."

"Anything I should know?"

"Well, I can't confess to be an expert in human medicine, but he seemed…well, not quite starved, but certainly ill-treated. And we felt a dark power from him during the night. We even heard strange noises and voices."

Rimuru nodded, or at least as much as a round blob of gel with no real anatomical features could. "Okay, I'll try to handle this."

He hopped into the tent where the human was, and peered at him. A teenager, by all accounts, and one who looked Caucasian. Wearing glasses too. Did glasses exist on this world? Hmm, he thinks he saw some being worn in Dwargon. What a nasty-looking scar on his forehead, though. And he looked scrawny and grimy.

Inwardly, he asked the voice that had accompanied him to this world something. Hey, Great Sage, could you check the kid out?

Acknowledged, the Great Sage said. After a few seconds, it said, ANALYSIS: Human male. Age approximately sixteen years old. Has magical ability, a recent hybridisation of magicule usage and a form of innate magic not native to this world.

Whoa! So he's an Otherworlder like me?! And he could use magic before he got here?

ANSWER: In all likelihood, yes. It seems more likely that he ended up in this world due to a summoning or by accident rather than by reincarnation. Current physical condition suboptimal, but not critical. Medical treatment advisable, but not urgent. However, there is something of considerable concern. The subject has at least one Unique Skill, and more data is required. But of more concern is his scar.

…What about it? What's wrong with the scar?

OBSERVATION: The scar contains a combination of dark magic of a kind not seen on this world, as well as the fragment of a soul. The nearest analogous term is a phylactery.

Holy crap! That kid has part of someone else's soul in that scar?

ANSWER: Yes. The malevolence in the phylactery is unmistakeable, and it acts as a parasite on the boy's life-force and magical power. However, it is possible that, with the careful application of your Predator Skill, this phylactery can be removed without endangering his life. The phylactery can be then analysed and destroyed within you. If nothing else, Veldora can destroy it.

Okay, let's go with that, then! Rimuru said. Hopefully, he'll be friendly to us. And a bit of gratitude for ridding him of this thing wouldn't go astray.

With that, directed by the Great Sage, he extended part of his form, and began consuming the thing in the boy's scar. It felt icky and shit, whatever he was nomming from the scar, but hopefully, it wouldn't leave a bad taste in his mouth. The boy convulsed a few times, as if the phylactery was fighting its removal, but Rimuru eventually finished.

Belching softly, Rimuru grumbled, "Ugh, the aftertaste is nasty. Can slimes use mouthwash?"

ANSWER: No mouthwash is available in this world. It would not affect your constitution either, due to your power.

"…That was a rhetorical question, Great Sage."

ANALYSIS: No, it was not.

"…Did you just sass me? Ugh, never mind. How's dealing with the phylactery going?"

PROGRESS REPORT: The phylactery is being broken down. Useful memories and abilities are being siphoned from it. Language: Parseltongue is one of them. It appears to be an innate ability to communicate with certain reptiles, specifically snakes. The boy retains that ability.

"Okay, cool, so, what about the guy this phylactery belonged to? Or girl?"

ANSWER: The phylactery belonged to Tom Marvolo Riddle Junior. Memories are fragmented, but analysis shows that he was born in the United Kingdom of your world. He became known and feared as Lord Voldemort, derived from an anagram of his name. A warlock who espoused blood purity, despite knowing himself to be a Halfblood, that is, a wizard with a parent with no magical ability.

"Yeesh, sounds like a Nazi with a chuunibyou nature. As if you could be any more edgy than a Nazi."

Voldemort was powerful and feared, but he was also extremely thanatophobic, obsessed with creating these phylacteries, which in his memories, he dubs 'Horcruxes'.

"Hey, dying sucks. Having gone through it myself, I can't blame him."

The ritual used to prepare the soul for fragmentation to create Horcruxes is a particularly vile one. It says much about how vile when the process of murder in cold blood to split the soul is less vile than the process leading up to it. It is extremely unlikely that you would wish to use it yourself. In addition, the process erodes one's mental well-being.

Rimuru grimaced at the thought. "So what was the Horcrux doing in this kid?"

ANALYSIS: Memories are sketchy, but it appears that Voldemort actually intended to create a Horcrux upon killing this boy. At the time, the boy was an infant, and Voldemort slew his parents. Somehow, the boy survived, possibly due to a sacrificial ritual his mother used, one where she sacrificed her own life. The Horcrux in the boy's scar was, in all likelihood, created by accident, as Voldemort wished to create one with the boy's demise, not use the boy as one. That marks the end of this Horcrux's memories.

"Sounds like a real charmer. Well, hopefully, the kid won't be bad, or too traumatised by what he went through. I mean, this'll probably be the big test of my 'don't hurt humans' rule. If the kid lashes out, it could be real messy." Rimuru sighed. True, he didn't technically have lungs anymore in this new life, but there comes a time in every sentient being's life when they need to sigh.

He just hoped he wasn't going to regret this…

Pain was too familiar to him, its ache throbbing throughout his body. It was more the pain of weariness, thankfully, but still…it was not fun. Not fun at all.

And then, there was the sudden burning pain from his scar. He was sure his heart stopped once or twice during that. And yet, once it was finished…he felt better than he had for a long time.

Still, when he woke up, he wasn't expecting to see what looked like a blue blob the rough size of a beach ball with squinty eyes peering at him. Nor was he expecting the blob to wave a tendril, and say, in a childish, androgynous voice, "Hey there! Don't worry, I'm a good slime, slurp!"

He stared at the blob. Of all the things for it to say, he wasn't expecting that. "…What."

The blob seemed to sigh. "…Hmm, maybe it was too much to ask for him to know about Dragon Quest. Then again, is it popular in Britain?" it muttered to itself.

He blinked at that. "Sorry, what? How do you know I'm from Britain?"

"Aside from the accent? Long story short, you had a fragment of someone's soul in that scar, someone who was apparently pretty nasty. So I ate it," the blob said, rather casually. "Does the name Voldemort mean anything to you?"

He felt a thrill of fear and repulsion. He had a fragment of Voldemort's soul in his scar? "Yeah. It does. Is it gone?" he asked, more calmly than he felt, sitting up.

"All digested and gone, turned into slime poop. Not that I poop anyway. Look, I know it may seem bad, but you're safe here now."

"And here is…where? I'm guessing I'm somewhere in the Great Forest of Jura, I was on the outskirts of that when I did that blind Apparition to avoid that monster, but…" He trailed off. He found himself uncertain whether he could trust this creature or not.

As if sensing this, the blob extended a tendril and gently patted his shoulder. "Hey…it's okay, kid. You actually are safe here. Believe it or not, I'm from Earth too. Japan, actually."

He felt his suspicions inflamed again. Perhaps unfairly, but still, he was wary. "So were the other three. I was summoned to some country, Falmuth, and those three…they were nasty pieces of work. Okay, I get it, we were abducted, but…they were Japanese. I'm not saying that's a reason to distrust you, only that I can't trust you simply on the basis of you being from Earth as well."

The blob flinched, or seemed to. "…Okay, that sounds like a hell of a long story. But I promise you, we won't hurt you. You're in the middle of a village I'm having built, one populated by Goblins…well, Hobgoblins now, and Direwolves, well, Tempest Wolves too. As long as you don't start anything, you're safe from us."

"…Even if you're telling the truth, I'm not sure you're safe from me," he admitted. "When I was summoned…I was in prison, for a crime I didn't commit. They claimed I murdered someone, and bunged me up in a prison where the guards are soul-sucking demons that bring up your worst memories and fears." His face fell. "Because of that, I gained a Unique Skill, called Nightmare Eden. I can manifest my worst fears and those of others into reality. And I barely kept control of it. Even with Falmuth's top mage putting a locking curse on me to control me, Nightmare Eden kept playing up, so they sent me to a fortress on the borderland between Falmuth and Jura, to prevent me from hurting them. Not that they didn't deserve it, they're a greedy and immoral bunch of bastards. We were little more than weapons to them."

He put his head in his hands. But once more, the blob patted his shoulder. "Hey. I get that you're not exactly trusting. Like I said, it sounds like a hell of a long story. But…I'm willing to help. This place is probably going to become a haven for monsters, but that doesn't mean humans aren't welcome. I want to help people, whether they be Goblins, Dwarves, Direwolves, or humans. Gimme a chance. We help each other, okay?"

It took what felt like an eternity to make a decision, though it was more a matter of seconds. His treatment both before and after coming to this world left him wary and suspicious. And yet…this blob thing…unlike those bastards in Falmuth, he seemed at least sincere.

Maybe he would give it a shot. It wasn't like he had anywhere concrete to go. "…Fine. Let's just hope neither of us regret this."

"Anyway, the name's Rimuru Tempest! Well, I was Satoru Mikami back in Japan, but that was before I got reincarnated as a slime! What's your name?"

"…Harry Potter…"

CHAPTER 1 ANNOTATIONS:

So, Harry's in the world of TenSura, and has met Rimuru. But how exactly did he end up there? And what happened in Falmuth?

1. I was trying to think of an interesting Unique Skill for Harry. This one, one of a couple, is named for the infamously camp Doctor Who story Nightmare of Eden, though its effects are closer to that of the Mind Parasite from The Mind of Evil.