Disclaimer: I don't own Yu-Gi-Oh! or Rise of the Guardians.

Content warning(s): non-explicit violence and mentions of mental illness. Also Season 0 Yami, who totally deserves his own warning.

Fun and Games

A Yu-Gi-Oh & Rise of the Guardians Crossover by The Half-Blood Guardian

Part 3

Nearly eight years later, Jack came by to see Yuugi again. He had visited the boy – now a teenager, even if his short stature and soft facial features didn't reflect his age – on dozens of occasions by now, though his visits had tapered off as Yuugi got older. It had been a few years since he had seemed to realize it when Jack was around, and it pained the spirit to know that he was being forgotten.

Still, Yuugi was one of very, very few humans who had ever routinely reacted to his presence, and that was something that Jack cherished.

Yuugi hadn't been at his home yet, despite the late hour, and Jack had decided to go out and look for him.

He had resolved to come see the boy more frequently after his last visit only a few weeks ago, when he'd overheard a quiet conversation between two of Yuugi's new friends. Apparently, the smaller teenager had been experiencing blackouts and moments where he displayed strange, out of character mannerisms. He'd been trying to hide it, but his friends were evidently beginning to catch onto the odd behavior.

Jack was many things, but after nearly three hundred years of existence, one thing he definitely wasn't was naïve. He'd seen a lot, including plenty of instances of mental illness, and knew that in most cases, signs of it began to manifest themselves in people who hadn't yet reached adulthood. In teenagers, like Yuugi. Sometimes it was curable, but often it persisted for the rest of the person's life.

He also knew that, despite medicine having progressed in leaps and bounds since the early 1700s, there was still so much that wasn't yet understood about the human mind, and therefore only so much that could be done to treat its illnesses.

It was sad, and he hated it, but if Yuugi was suffering from some sort of undiagnosed mental disorder, then realistically, there was nothing Jack could do for him.

The winter spirit shook himself from his thoughts, eyeing the setting sun with apprehension. There really weren't many places in the world where being out after dark was remotely safe, and Yuugi was an obvious target at the best of times. He hopped to the next rooftop over, Wind whistling around him encouragingly and helping him make the leap. A small smile ghosted across his lips, and he quietly thanked his only friend.

An angry shout had him turning his head, and Wind carried him closer to the sound. He briefly touched down on a lamppost, waiting for the voice to speak again. He didn't have to wait long before he heard another deep voice, this one jeering, and then a third one, anxious and small, stuttering a reply. Finally he landed on a rooftop next to a dim alley, because something shady was obviously going on, so of course it was happening in an alley.

It was dark, but he could make out three separate figures, two of them much larger than the third, which was backed against one of the grimy walls. Jack looked closer at the smaller figure and caught sight of a mess of spiked, multicolored hair and the glint of a gold trinket. He almost sighed. It was Yuugi. Because why wouldn't it be?

Much like his real-life experience course on mental illnesses and human frailty, Jack had eventually been forced to realize that sometimes – most times – he couldn't save the people he found in trouble. While a sudden burst of cold wind and snowflakes where the temperature had previously been mild was certainly enough to unsettle attackers, it was rarely enough to scare them off completely.

Even so, Jack couldn't help but watch and hope he could make a difference if things got too out of hand.

It turned out that the two shady individuals weren't actually after money. Neither of them seemed to care much when all they got from Yuugi was a bit of spare change, and simply went on harassing the poor boy. Jack gritted his teeth and wrinkled his nose in disgust. He himself was quite the prankster, but he only pranked people he knew could take it, and there was never any truly malicious intent behind it. People who cruelly tormented others for no reason besides their own amusement were a whole different story.

Jack stiffened when one of the thugs decided that simply shoving Yuugi around was boring and landed the first punch. The second thug apparently thought it was a good idea, as he soon joined in. Yuugi cried out, squeezing his eyes shut and curling in on himself, and Jack was one second away from jumping down there when the feeling of menacing power suddenly encompassed the alley, stealing his breath and causing him to land on his rear. Staring down with wide eyes, he saw a wall of darkness shoot up between the humans and the mouth of the alley, which was suddenly twice as dim as before.

The two thugs had stopped, surprised by the change. Jack looked at Yuugi to see his reaction. The boy had uncurled but remained oddly still. Shadows obscured his expression, and–

His head shot up, eyes snapping open to reveal irises that swirled red and wild and furious.

A snarl ripped past bared teeth, the sound making the back of Jack's neck prickle and his hair rise in a way that the cold would never be able to cause.

The sequence of events that followed were as confusing as they were terrifying; something was happening between the boy and his two attackers-turned-victims, but whatever it was, it seemed to be going on only in their heads. Judging by the dark and downright terrifying energy swirling in the air, though, it couldn't have been anything remotely pleasant. After an undetermined amount of time, the energy suddenly spiked before settling down to a barely detectable level, the wall of darkness dissipating.

In place of the energy, the air was suddenly filled with screams and cries and babbling, the thugs wild-eyed and frantic for no apparent reason, staring at things that Jack couldn't see and that most likely weren't even real.

The boy simply stood before them and watched for a few seconds with a wide smirk, then straightened his jacket and turned on his heel. Unbidden, the words spoken between Yuugi's friends came to Jack's mind.

The glimpses they had caught of abrupt changes in his personality, the memory lapses he'd been troubled with; both were indicators of possession. Or a wicked case of Dissociative Identity Disorder, but something told Jack that wasn't the case. Maybe it was the overwhelmingly dark energy, or the way the kid had literally gained a few inches of height, or how he'd somehow caused two other humans to go insane with little to no effort, or that his eyes had changed color, or that a gold, glowing third eye had temporarily materialized on his forehead. Yep, the boy was definitely being possessed by an immaterial spirit.

Immaterial spirits, unlike material ones such as himself, were invariably the remnants of people who had died with unfinished business, and whereas spirits of Jack's variety were only intangible to humans who didn't believe in them, immaterial spirits were fully, truly intangible, unable to physically interact with anything without the use of a host. Because of this, they were often looked down upon as inferior by material spirits. Jack would've felt indignant for their sake, except that he had never met one who wasn't a jerk to some degree.

At least this one didn't seem to want his host harmed, and had cared enough about the boy's well-being to take care of his attackers. Which was… sweet? Sort of? Okay, "sweet" definitely wasn't the right word to use here. But whatever the right word was, it was something vaguely positive, so the winter spirit may have even thought of the other as a decent guy. That is, y'know, if he hadn't just driven two guys insane while all but cackling with perverse delight. That kinda put a halt to any camaraderie or olive branches Jack might have eventually extended before he could even begin to contemplate offering them to the other spirit.

He watched warily from the rooftop as the immaterial spirit stepped out of the alley and walked a short distance down the sidewalk. Then piercing eyes swept the area, and Jack guessed that the only reason he wasn't detected was the fact that he was much better at obscuring his presence than a human. Once the red eyed spirit was satisfied he was alone, he closed his eyes, and for the first time that night, Jack saw his posture relax. Soft, violet eyes blinked open, and after glancing around in confused worry for a moment, the young teenager headed home at a brisk pace.

And if Jack followed from a distance until he was safely inside the game shop, well, that was no one's business but his own.

(because if I'm going to write a Yu-Gi-Oh crossover with Season 0 as part of the timeline, you better believe there's gonna be someone from the other fandom gawking at Yami's savage murder/insanity games)