To put that number into context: most of the longest novels ever only have a little over a million words in them. And this fan-fiction has nearly three times as many words as that.
Yeah. It's kind of unreal.
Maybe you've heard of it? It's been around since 2008, after all. If not, it's called The Subspace Emissary's Worlds Conquest, and it's written by AuraChannelerChris. Subspace follows OC Chris and the Pokemon Lucario, who "embark on a quest to stop the Subspace Emissary from taking over all the worlds." That's a quote from the fic's TV Trope page: yes, this thing even has a TV Tropes page, and a lengthy one at that.
So the fan fic is long. But what of the quality? I'll let you decide; here's a small excerpt from an update on July 3rd of this year:
The flying fist about to crash and crush Chris's head against the invisible wall made his body react, diving to the left. The Lucario Noise struck the wall with its fist, and it miraculously didn't break. Breathing hard, Chris's eyes froze on the feral Noise still with its fist resting on the wall. When the red, empty eyes stared down at the World traveller, he screamed, scrambled up to his feet, and ran south as he heard the monster growling with anger, its clawed hands glowing with a purple aura.
"W-what now?!" Chris asked, not wanting to take a look at his pursuer. "I'm boxed in with a beast who wants to kill me! Where the hell should I run to?! I can't outrun him! If they based this Noise on Lucario completely, wouldn't that mean he's inhumanly strong?!" he asked to himself, stopping short when the Aura Hunter appeared right in front of him, having used ExtremeSpeed to defy speed. Yelping, Chris reared back, but the monster slapped him hard on his face, sending the teen to the right side where he crashed hard against the wall.
Chris was nearly fazed by the slap and the crash as he slid down to the concrete, his Black Mage hat falling to the side. He knew the monster was going easy on him, but it didn't look like that anymore once he heard the Noise growl a war cry and slamming its clawed feet as it made its way to him.
His mind racing with fleeting thoughts, Chris looked around and then found the entrance of the music store. Though a small touch of his head revealed that a bleeding bruise was somewhere in his hair, Chris shivered with fear and made a run for it inside the store. It was unknown to him if it was possible to seek shelter inside a building with a Reaper decal, but there were no other options. Caring for his life over anybody else's, Chris took the decision to enter the store, its double doors opening automatically at his feet's request.
Briefly, a cold but strong hand grabbed his neck collar, but when he made it inside the store, the dark hand lost its grip when it reached the boundary of the decal's shield, an invisible wall pushing it back. When Chris noticed that the stomping feet seized their chase, he looked behind and saw the fully-angered look of his predator. The Aura Hunter growled with power to the sky, demanding his prey to come on outside.
The terrifying sight made Chris feel very sick. The feral monster then charged an Aura Sphere that took several seconds to finish. Yelping, Chris dove to the right and barely saw the sphere of destruction vanishing when it came into contact with the decal's barrier, not even causing an explosion. The effect of the barrier only caused the Lucario Noise to growl loudly. It then began to shoot Aura Sphere after Aura Sphere.
Chris gulped and looked back. The Noise was stubbornly trying to attack him from the outside. It was obvious since the Aura Spheres, which Chris noticed were a shade of purple instead of a calming blue colour, were clearly going to his direction. Nonetheless, the barrier separating the world of the living and the world of the dead negated the murderous blows.
While some may find the existence of this fic baffling, it makes sense. Jason points out that Smash Bros is basically fan fiction in game form: "Sonic beats up Mario" and "Peach throws a turnip at Ganondorf" are the kind of normal, everyday things that happen in the game. Crossovers and unlikely, sometimes ridiculous situations are basically the appeal of the game, much like what fanfiction tends to do.
If your interest has been piqued, you can read the start of the fic here.