So, a chapter of a story that isn't a Nasuverse crossover. Rejoice!

Followers of my writings may remember a crossover I did with Batman: Arkham Asylum called Yin and Yang, one I eventually abandoned and stuck back in here in the Cauldron. Having started to play the games again, I decided to see if I could come back to it as a possible crossover. But instead of having Harry as a hero in Gotham, I thought I'd have him as an amnesic inmate of Arkham Asylum.

Now, I am far from the only person to have Harry in Arkham in their fics. But I think that nobody has inflicted him with amnesia for such fics. While I am drawing on the likes of RobSt's You're My Density and Temporal Knight's Potters Against the World, I am not having the time travel of either of those. In fact, this is more based on DZ2's 'Forget Me Not' challenge, and Harry's demeanour as 'John Doe' was also influenced by the characters of 'Haise Sasaki' from Tokyo Ghoul: re and Bob Arctor/Fred from A Scanner Darkly. Hell, my chosen theme song for this story would be Dima Lancaster's cover of Asphyxia, the first opening song for Tokyo Ghoul: re.

This will be a Harry/Ivy/Harley story, eventually. It's why I left Harry in Arkham until he was 21. Both Ivy and Harley are in their early thirties at the very least, if the timeline on the wiki for the games is any indication.

Anyway, I hope you enjoy. The title can mean either a cross-cultural marriage (and a relationship between a former wizarding messiah, a sexy insane jester, and a chlorokinetic eco-terrorist sounds like one hell of a culture gap), or the process of cross-pollination, a reference to Ivy and Harry's relationship.

EDIT: After writing the first seven chapters of this story, I realised that Harry was too passive. So, I've changed things up for the revised version. Watch this space...

XENOGAMY (ORIGINAL)

CHAPTER 1:

JOHN DOE

If there was one thing the vigilante known as Batman hated, aside from crime, chaos, and killer clowns, it was a supposedly unsolvable mystery. Especially one where a crime was involved, and he wasn't sure who the criminal was. Not in the sense that he didn't know the perpetrator, but rather, whether the perpetrator was actually the perpetrator.

Batman, or rather, Bruce Wayne, looked at the images on the screens of the Batcomputer. All his technology and resources, and he couldn't find out who this young man was, or who he was supposed to have killed. Official channels were stymied, unofficial channels were fruitless. The identity of the young man known to him and the staff of Arkham Asylum as John Doe was a mystery, even to John Doe himself.

John Doe appeared to be a young man in his late teens or his early twenties. According to the only known data on his file, his birthdate, he was 21 years old, if the data was accurate. A shaggy mop of dark hair framed haggard features, emerald eyes peering out from behind glasses. A scar, in the shape of a lightning bolt, snaked its way from under his fringe.

The pictures captured little of the strange attitude of the young man. He seemed placid and passive, almost like a lobotomy patient, and yet, he had a strange stubbornness and strength of will that Arkham Asylum hadn't stifled. Bruce had only met him a few occasions, most of which had been at Arkham itself. Despite his youth, he had been used effectively as a trusty. That sort of thing had been abolished in the US since the Seventies, but Gotham's corruption still stained many parts of the city, as did penny-pinching. The young man acted as a de facto gardener and caretaker of Arkham Asylum's botanical gardens, which he seemed to do a good job at, given how he caught the eye of Poison Ivy, the villain formerly known as Dr Pamela Isley.

Depending on whom you spoke to, opinions on John Doe varied. Aaron Cash and the better guards pitied the boy. The more contemptuous ones denounced him as a zombie, faking amnesia to get away with his crimes. Warden Sharp refused to be drawn on John Doe.

As for the villains who were often inmates at the asylum, well, again, opinions differed. Oddly enough, the Joker and Harleen Quinzel, aka Harley Quinn, had differing opinions. The Joker despised him, and Harley reckoned he wasn't such a bad kid. This difference seemed to stem from one of the few violent incidents involving John Doe (as a participant than a victim, anyway), when he happened to be moved through the patient intake segments when Joker and Harley were being processed a couple of years ago. When Joker attacked Harley, John Doe came to the rescue, attacking Joker with perhaps more enthusiasm than actual strength. He did manage to give Joker a rather painful blow between the legs before the guards separated the three, though.

Of course, things changed about a year ago. Ivy escaped Arkham Asylum. However, unlike the previous times she had been incarcerated, she had taken a fellow escapee with her, namely John Doe. Nobody really knew why, save for Cash, who had observed John Doe speaking to the plants. Not in a way that suggested that he was conspiring with Ivy, but rather, more in a conversational manner. Considering that, for the most part, Ivy was confined to a special quarantine cell in the penitentiary part of Arkham Asylum, far away from her plants, well, all she could do was perhaps sense through them, and occasionally speak through them.

Thankfully, Cash only shared this observation with Bruce and Commissioner Gordon, along with one of his trusted officers, William North. Cash didn't trust anyone else with this information, especially not the warden nor his cronies. Sharp was a wannabe politician who was angling to get elected mayor, and was prickly over anyone prying into his affairs, which suggested to Bruce a number of skeletons in the closet, one of them being John Doe.

However, although there were initially signs that Ivy was planning something big, she then went silent for a considerable period. And when she did make herself known, her attacks were targeted, even if they were somewhat brutal. But Ivy's actions suggested something more catastrophic and indiscriminate was intended initially.

Bruce soon believed he knew the cause: John Doe. Somehow, the young man's actions in tending to Ivy's beloved plants had earned him not inconsiderable favour from the former botanist. She had taken him probably not because he was a potential accomplice, as Ivy's attacks seemed to be performed alone, with little help save for that from her plants, but perhaps out of sentimental value.

He knew she was capable of such a thing. After a devastating earthquake some years back, she had sheltered a number of orphans in Robinson Park, without any other reason other than the vestiges of her altruism. Despite her misanthropy, she still had a soft spot for children. It seemed that John Doe had been added to the list of people she would trust.

Bruce knew that, despite rumours and allegations by the ignorant and bigoted, Poison Ivy was not a lesbian, but rather, bisexual, albeit with a preference towards women. While she had some misandry, she was actually more of a strong misanthrope, someone with an axe to grind against humanity in general, with few exceptions. It was a slim possibility that she had taken John Doe as a lover. Then again, it may be that she just wanted a decent gardener to look after her plants in her hideout, and she didn't mind using him as someone to talk to.

Either way, John Doe was a possible key to Poison Ivy's rehabilitation.

Bruce detested the vicious cycle, where villains would end up in Arkham or Blackgate, only to either break out, or fake rehabilitation, only to revert back to their villainous ways when people's guards were down. And sometimes, they'd actually genuinely try to rehabilitate, only for circumstances to conspire to force them back to a life of crime. While he wasn't sure the likes of Joker, Scarecrow or Killer Croc would ever be rehabilitated, there was the possibility, no matter slim, for people like Two-Face, or Mr Freeze. Maybe there was hope for Ivy too.

The question was, was John Doe truly guilty of the crimes his rather sparse file had? Or was the rather quiet, passive young man another innocent, railroaded by the corrupt system of Gotham?

Bruce knew some things about him. John Doe had a British accent, one that seemed to put him in the vicinity of London and its suburbs. Not the harsh, affected Cockney-like accent of Oswald Cobblepot, but a softer one. His medical file listed some basics, that he had apparently suffered from malnutrition and physical abuse, given the growth of his body and the scars. But there was very little, and Bruce had other, more urgent cases to deal with than a mysterious John Doe who may or may not deserve to be in Arkham Asylum.

But now, while not quite a priority, Bruce made sure to actually look over the files, and find new angles. His admittedly limited access to British police files, to say nothing of public records, had turned up little. Then again, all he could go on was a possibly faked birthdate and a physical description.

Anyway, Bruce had managed to track down and capture Ivy. He really did understand why she had such a grudge against the industrialist she was trying to murder. He'd been working on exposing the man's blatant flouting of environmental protection laws, both as Batman and Bruce Wayne, and the man had used mob connections to have more than a few people killed, including a couple of journalists and an inspector who couldn't be bought off. Ivy had jumped the gun, though. She was also reluctant to say anything about where John Doe was, but he managed to find her current hideout. And there, he found him…

Bruce knew to be wary around Ivy's plants. Even without their mistress, many of them would be wanting to turn him into an unwilling participant in a botanical-themed tentacle hentai. So when he entered the glasshouse on the outskirts of Gotham, well away from her usual haunts, he was ready for almost anything.

However, he soon found John Doe, watering a writhing plant, as if he was a gardener on an estate. A flash of an image of Alfred watering a flower sprang to mind. He was standing there, no longer in his Arkham Asylum jumpsuit, but simple clothes, a shirt and trousers.

And then, he spoke. "She told me you were coming. She wanted me to go to ground, hide out with Harley, given that the Joker's still at Arkham, for now. But I hadn't finished watering her plants. Besides, I've committed no crime, that I can remember."

"Escaping from custody is a crime," Bruce said.

"Escaping from lawful custody is a crime," John Doe said, moving onto another plant. "So…is the so-called Great Detective that sure of my guilt? Were you the one who chucked me into Arkham, leaving me with no memory of why?"

"I don't know who you are."

John Doe scoffed bitterly. "Of course not. If I don't know who I am, why would the goddamned Batman know? I'm not going to fight you. What's the point? I'll end up with bruises and a concussion at least. Just let me finish this off first. I've set up an automatic watering system so that Pamela's plants get watered while she's away. Saves Selina from having to remember to come around to water her favourite flowers."

As the young man moved around, Bruce kept an eye on him for any suspicious moves. But there seemed to be only weary resignation. "…I could find out who you are, and find out whether or not you are guilty of any crimes," Bruce offered, on an uncharacteristic impulse. Then again, the young man's situation had piqued his curiosity. "If you are innocent, then I will do my best to exonerate you."

"…And what about Pamela?"

"She is a convicted and unrepentant murderer," Bruce said. "She will be staying in custody for a long time. However, you could be key to rehabilitating her, assuming your friendship is something more than hybristophilia or Stockholm Syndrome."

John Doe scoffed. "…Pamela and I discussed that. Hybristophilia is what Harley has, having a thing for criminals. If I have Stockholm Syndrome, then Pamela has Lima Syndrome. Hostage and hostage taker identifies and sympathise with each other respectively. If it weren't for me, she would have killed a lot more people. Not that you care."

"…If you did, that is better than nothing. Come quietly, and I promise, I will help find out who you really are."

Once more, the amnesiac young man scoffed. "Don't make promises you can't keep, Batman…"

Bruce was brought back to reality when Alfred came up to him, only to remark, "Dear Lord…is that…?"

Bruce turned to Alfred, who was staring at the image of John Doe. "…John Doe, a mysterious inmate at Arkham Asylum. A trusty, unofficially, who maintains the botanical gardens there. Ivy seems to have taken a shine to him." Then, Bruce asked the million dollar question. "You know him, don't you?"

"…I may, though it's only a hunch, based on those features and that scar. Why are you looking into him, Master Bruce?"

"…He has virtually no records, save for a birthdate, some medical examinations, and charges of murder against him," Bruce said. "He was incarcerated in Arkham in August 2006. Five years ago now."

"…I believe I know where he came from. And I would not be surprised one bit if the charges against him were completely false, or at least exaggerated."

"How do you know that, Alfred?"

"…Master Bruce, I have often avoided speaking of my own past for various reasons. I told you that my family disowned me, with my entering the armed forces afterwards. However, what I did not tell you was that my family was once a long and illustrious line of mages."

Bruce frowned. Magic was not something he liked to have much truck with, though he knew Zatanna and John Constantine. "Why were you cast out?"

"Because I am what they call a Squib, a person born to a magical bloodline who can't use magic. However, I have kept abreast of events in Britain on that side of matters. John Doe, as you call him…well, he suffered a not-dissimilar fate to you, Master Bruce. At the age of one, he and his family were targeted by a wizard terrorist by the name of Voldemort, who murdered his parents. However, Voldemort died in attempting to kill their infant son, who had only a lightning-shaped scar to show for it. He became famous as the Boy Who Lived…but his star fell spectacularly five years ago. He'd been forced to participate in a magical tournament, and he disappeared, only to reappear, with one of his fellow contestants dead. He claimed Voldemort was back from the grave. However, the government not only didn't believe him, but eventually accused him not only of the murder of that fellow contestant, but other crimes. He disappeared soon after his trial, which was something of a kangaroo court. While it is possible he was guilty, magical governments are almost as corrupt as Gotham used to be. Nobody knows where he ended up."

"And you believe John Doe to be this person?"

"Very likely. The birthdate is the same, 31st of July, 1990. The scar, the hair, his eyes…if it's not him, I will be surprised," Alfred said. "However, I would not be surprised if proving his innocence is near-impossible. While the regime that sent him to prison is now gone, along with Voldemort and most of his followers, the British Ministry of Magic don't take kindly to non-magicals meddling in their affairs. Neither does MACUSA, the equivalent here in this country. And Magical Britain is still divided about his innocence. Some believe what was thrown about by him, while others, especially now, have worked to exonerate him. If he is in Arkham, without his magic or memories, it'd explain a lot. They probably sealed his magic, erased his memories, and shipped him off here to keep him quiet."

"I'm hearing a lot about his life, Alfred, but I'm not hearing a name. I presume he has one outside of John Doe."

"Of course sir," Alfred said, Bruce's snark doing little to ruffle his feathers. "It's not a particularly remarkable one, though, save to wizards. His name is Harry Potter…"

CHAPTER 1 ANNOTATIONS:

Oh dear. Batman's gonna be opening a can of worms rather than a can of whoopass.

No numbered annotations this time.