Hey, everyone! This is the first chapter of my brainchild: a Harry Potter/Heroes of Olympus crossover. It's enormous, and I've been working on it for a few years now, so it's pretty well thought-out. It's not totally written after a certain point a few chapters in, but don't worry about me abandoning it—I've spent three years working on this already, so what's another few? It's not huge on romance (the only romance is a side plot), but it's about friendship, family, and everything in between. Death's Apprentice has Greek, Roman, and Celtic mythology mixed in with the Harry Potter-verse, but I've done pretty heavy research on all of it. That said, mythology is convoluted and contradicting on the best of days, so your version may be different from mine. Nonetheless, let me know if you have any issues with what I've written! And with that, I hope you all enjoy the story!

I never wanted an apprentice.

Really, it never made sense to have one. I'm immortal, after all; what's the point of training someone to take your place if you never intend to step down? Besides, I've always been quite capable of handling my job on my own, so it wasn't like I needed the help. My job pays well, has plenty of benefits, and happens to come with a lovely office and a nifty little coffee machine that I didn't fancy sharing with anyone.

Was I lonely? I suppose so. Frankly, one doesn't realize that they're lacking in something until they've had it, and I'd never had companionship, so how was I to know that I longed for it? And anyway, having an apprentice wasn't exactly "companionship," in my mind.

How was I to know that the teacher could become the taught, that a master and apprentice would become more like family than coworkers? How could I have known that "Master Thanatos" could become "Uncle Death," or that an apprentice could turn into the closest thing I had to a daughter?

Well, I couldn't, and I didn't. And it took a while for me to realize what a beautiful gift I had been given, in the form of freckles, electricity, and a love for coffee that matches even mine.

As for my favorite apprentice-here is your story (our story!), and it all begins with this chapter:

How I Met Your (Great) Grandmother. Again.

It was supposed to be a normal day.

Granted, a normal day for me is usually started with coffee and ended with paperwork, so the fact that Lord Pluto sent me out of the Underworld in the first place was already out of the ordinary. Still, by all rights it should have been straightforward: I simply needed to corral the souls of a young family who had been murdered by some sort of mortal serial killer-Voldemort, he had called himself. Usually I'd send my Dementors to collect their souls, or sometimes Hermes, but I was curious how three murder victims fell into my sphere of "peaceful death."

So I went to their dying place and quickly discovered that the household of the murder victims simply didn't exist. At least, it didn't appear to, since it was coated in an extremely dense layer of Mist and something that inexplicably reminded me of the goddess Hecate (or Trivia, if you're one of those Roman purists). However, I'm not a god for nothing, so I was able to at least find and enter the house after five or so minutes of intense squinting.

The moment I stepped in the door, the stench of death hit me. Not a mortal's death, although that was present as well, this being the site of a murder and all. No, this was the smell of an entity of death, a god or goddess or someone of that nature. Being the ever-intelligent and sharp-witted god that I am, I figured that I had farted without realizing it. After all, what reason would entice a different death deity have to enter a house in the domain of Pluto?

The answer was, as it usually turns out to be, love and a deep-rooted desire to piss Jupiter off.

The first corpse I discovered was that of a young man, likely around twenty-one, with wide eyes frozen in place and no mark upon his body. His ghost was sitting on top of the body, unruly hair and glasses askew as they would have been in real life.

"Hello," I said to him. It wasn't polite to speak ill of the dead, and it wasn't polite to speak ill to the dead, so manners it was. "Might I ask your name?"

The man looked startled. "James," he said. "James Potter."

"Fine name, that," I said approvingly, shaking his hand. "I am Thanatos. If you don't mind me asking, how did you die?"

James sighed, pushing his ghostly glasses up the bridge of his nose. "Voldemort," he said bitterly. "Our Secret Keeper betrayed us, and I didn't have my wand on me."

I froze. Wand-wielders, huh? Hadn't seen those in a while. I'd heard rumors of a Killing Curse that could kill someone instantly and painlessly, which was likely why I'd been summoned rather than my more violent counterpart. Still, wand-wielders usually fell into the Celtic sphere, not the Greek or Roman, so why was I here instead of the Triple Goddess?

I shook myself, forcing a smile on my face. "Well, James," I said jovially, "looks like your time in this world is up. I'm going to take you down to the Underworld now, if you'll allow it."

I'd take him down to the Underworld whether he allowed it or not, but for some reason, pretending like mortals had a choice aided the transition.

James nodded slowly, though he looked somewhat terrified. "What about my wife and daughter?" he asked hesitantly. "You're not taking them, are you?"

There were other dead souls in this house, I knew, but I wasn't going to tell that to a dead man. "At the moment, in here for you, James," I said in the kindest voice I could muster, which is not very. I did try, though, and that's what's important.

He seemed to accept that, and I pulled him into the bag of souls I carried on my belt.

The other souls were upstairs, so I let my feet leisurely stroll up the hardwood steps. Cheerful pictures hung on the wall, most with three main figures: James, a lovely woman with dark red hair who I presumed was his wife, and a tiny baby with bright red hair and startlingly familiar blue eyes.

The door at the end of the hall was cracked open, and I saw shadows flickering in the dim light, which was odd, as it was only seven or so in the evening and shouldn't have been that dark. I merely added it to my list of "strange but relatively unworrisome" facets of this particular field trip.

I slowly pushed the door open and scanned the room. It seemed to be a nursery, with colorful wallpaper and stuffed animals in a small stack near a wooden crib. It would have been quite homey had the dead body of the woman from the pictures not been collapsed in front of the crib.

"Afternoon," said the woman's ghost irritably. Her eyes were a piercing green, and to be perfectly honest, they felt a bit uncomfortable, as if they could see straight through my mortal guise to the skull face underneath. She was also at least four months pregnant. "I suppose you're Thanatos, then."

Odd that the woman should be familiar with my name. Actually, I was a little flattered. "That would be me, yes."

"Well," she said dryly, "if you're here for my soul, I'm afraid you're going to have to fight my grandmother for it."

I shifted. "I don't understand-"

A sword materialized at my throat and hot breath washed over my neck. "Hello, Thanatos," said a raspy, though clearly feminine, voice. "Miss me?"

Time slowed to a stop. I knew this voice as well as I knew how to operate my coffee maker: The Morrigan, one of the most powerful Celtic deities, perhaps seconded only by the goddess Brigid, and a death goddess, to boot.

"Hi, sweetheart," I said.

Oh, and she was also my on-and-off girlfriend for the last few centuries.

"Don't sweetheart me, Mister," she snarled, digging the sword into my neck.

I licked my lips nervously. "So what brings you to my crime scene, milady?"

"Family," said the Morrigan, almost immediately. "As it usually is."

"That right?" I screwed up, I screwed up, I screwed up…"Could you maybe remove your sword and we can talk this over like men-pardon me, women?"

She seemed to consider it. I felt, rather than saw, her head tilting to the side in thought, followed by a deep sigh. "Why not?" she said tiredly, letting her sword arm drop.

Movements from then on had to be slow, cautious. The Morrigan was far more powerful than I, even though the Celts had lost much of their power as the Greeks and Romans gained theirs. I turned to face her carefully, hands held up in a gesture of surrender.

The Morrigan was, without a doubt, the most beautiful woman I had ever laid eyes on, and I knew the goddess Venus. It may be that my infatuation was caused by her being a death deity and not a love goddess, or it could have been that if I didn't think she was gorgeous, she'd have murdered me two hundred years ago, but none of that stopped her from being extremely hot. Physically, she resembled James Potter's wife closely. They had the same dark red hair and intense green eyes, but the Morrigan seemed...wilder. Her hair was loose and tangled, her posture proud and unyielding, and her eyes seemed sharp enough to cut diamond without gaining a scratch.

"So let's talk," she said, leaning in threateningly. Her breath smelled of blood and carrion.

It was intoxicating.

"Thanks for not killing him, Grandmother," said the woman's ghost. "I don't really want Addie to see you lop off someone's head."

The Morrigan snorted. "She'll see it once she gets a little older, anyways, Lily darling."

So the woman's name was Lily, and the Morrigan was her grandmother. Interesting. So then why was a Greek and Roman god of death summoned, when it was quite clear that this family was under the domain of the Morrigan?

"I'm assuming you're wondering why you were called here," said the Morrigan, interrupting my thoughts.

"It had crossed my mind."

The Morrigan jerked her head towards the crib. "Go take a look," she said bitterly. "But if you make any kind of move-"

"I won't, I swear!" I protested, carefully weaving my way around Lily Potter's corpse to peer into the crib. Inside it was the baby from the photos in all her red-head glory, but it was her eyes that stood out the most. They were the same shade of blue as in the pictures, but in person it was much clearer why they had seemed so familiar. Her eyes were the brightest and most vibrant shade of blue imaginable. One might even go so far to suggest that they were electric blue.

"I see Jupiter has been busy," I commented, rubbing the crease between my eyebrows.

"In my defense," said Lily, "I honestly didn't expect the baby owl to turn into a Roman god. And Jupiter was really flexible-"

I yelped and covered my ears. "Yeah, I don't want to know how the man upstairs is in bed, thanks!" I said hastily. "And what about your husband, James?"

Lily shrugged. "We weren't even dating at that point. We only started going out after Addie was born."

"I...see," I said finally, feeling a new respect for James. It takes a special kind of man to date a woman with a young child, especially when said child was the daughter of an extraordinarily powerful and terrifying Celtic legacy-oh, and Jupiter, too.

"So what now?" Lily asked, folding her ghostly arms and leaning back against the baby's crib.

"Now I take your family's souls to the Underworld-"

"Not happening," said the Morrigan. "I'll take them to the Otherworld."

"The baby's a daughter of Jupiter," I said. "Underworld."

"Addie's a great-granddaughter of the Morrigan," she argued. "Otherworld."

"Daughter is closer than great-granddaughter. And I've already got James."

"Keep him. I'm taking Lily and Addison."

"Pluto, no," Lily said, having been relatively quiet for a few minutes. "I'm going where James is. And Addie's not dead."

I glanced back at the red-headed baby and examined her "death aura," as I like to call it. She was right; Addison wasn't completely dead. "She is mostly," I said.

"Mostly dead isn't dead," Lily pointed out triumphantly. "Just almost."

I hated it when dead people were smart. "Well, she's dead enough to take to the Underworld," I complained.

"She's dead enough to take to the Otherworld," replied the Morrigan.

"Gods almighty, will you stop that?" Lily said, her voice rising in frustration.

"Fine," said the Morrigan. "I'll raise her and she won't go to the Underworld or the Otherworld."

"I wouldn't trust you to raise my dog," I said instantly, "and mine's a zombie."

"Oh, like you could do better," scoffed the Morrigan.

"I bet I could," I said, puffing out my chest.

"You're on. We both raise her and see who's better at it."

"It's a bet," I said, sticking out a hand and shaking hers. We glared at each other for a minute, seeing who would blink first, before she grabbed the front of my robes and yanked me into a very long, very drawn-out snog.

"Oh my gods," said Lily in horror. "I cannot believe you two are going to be raising my baby."

We broke apart, breathing heavily. Her grin was predatory; mine was deliriously loopy.

"Wow," I said under my breath, feeling dazed. Suddenly, what I had just agreed to struck me, and I said several archaic curses involving miniature horses and Jupiter's underpants. A baby?!

"I have no idea what you just said," Lily muttered, "but I highly doubt it was appropriate for a one-year-old baby."

"Not really, no," I agreed, still shell-shocked.

Lily sighed. "Right," she said, "so I'm going with James to the Underworld."

"Uh-huh."

"And you two are taking care of Addie."

"That's right," said the Morrigan unaffectedly. "And I'll train Addison, don't you worry, dear."

Lily shook her head hurriedly. "Yeah, that's not happening," she said. "Nana, no offense, but you taught me the most effective ways to murder someone when I was four, and then said you should have started earlier. I want Thanatos training Addie."

"But Thanatos is a wimp," the Morrigan complained. "He won't let her fight battles until she's at least ten!"

"That's the point, Nana."

"Ugh. Fine." The Morrigan turned to me. "Looks like you have a new apprentice, Thanatos."

"Sounds like," I said faintly.

My new apprentice cackled maniacally, then started wailing.

"First things first," Lily said. "Do either of you know how to change a diaper?"

Phew. Chapter 1 is up! What did you guys think? Just FYI, the Otherworld is sort of like the Celtic Underworld, although it might be closer to the afterlives of the Norse myths on Yggdrasil, and the Morrigan is the Celtic Triple Goddess of Death, and one of the major deities in the Celtic pantheon.

I don't know when I'll update next: I'm still in school and have a very busy schedule. I'll try to update a few times a month, but I also have a chronic illness that acts up and causes me to miss a lot of school, so we'll see how it goes. Don't worry, though—this story is my baby and I won't be abandoning it in the foreseeable future.

Next Up: Death's experiences with parenting and Addie's new friend.