Picture of Warui
Warui is a corrupt spirit birthed from evil and hatred. Warui represents all things Implode, everything Asplode, and is especially known for Wa. Warui's "children" are the Wario and Waluigi (plus the lesser known Wapeach), so you know Warui is also no good. This being's ultimate goal is for everything to become Wa. Many compare him to The Devil, tempting people with power in exchange for control over them. Although you could say Warui's a slave to all the Wa-Guys and not the other way around because he has to give them some power.
The only things known about Warui's appearance is that it's purple, once had wings, and Asplode Implode Tinky Winky is the closest looking material form of it we'll get to ever see.
Origins[]
Back in ye olden days (about 4460000000 BC), cucumber salad mixed together with sour cream, garlic, stardust, and Plotholium. This created all the WA of the UnMultiverse. At first it was just concentrated in just a few mold spores, but then the WA realized it could manifest in other things. This "WA" would later be known as Warui. For billions of years Warui would fight itself in Counter-Strike, but then got bored and wanted to share some of that WA! (Not really, because Warui was just a sad ghost who did nothing all day.) So Warui used some gravity and some WA to mix elements together to make his first batch of influencers back in the UnWorld.
Wario was created from pure WA as well as tungsten. Waluigi was made from tungsten, thorium, uranium, potassium, and also WA. (They all had a lot of Γ radiation). Them, not knowing of their true creator would be especially useful for manifesting its destiny, as Warui foresaw that if Wario or Waluigi found a magic machine, they'd improve and abuse it, which is why it trapped itself in a blender. But Warui was impatient and that was taking forever, so Wapeach was also made to try and spread the wa-influence, but that never went anywhere. Luckily the blender thing did happen as according to plan, and that was how Wario created the Wa-Machine. (Thus making Wario its favorite.)
Possession[]
After some time, Tinky Winky would be put into the Wa-Machine and thus would start to become more and more under Warui's influence, enough to where WaWaWaWaWaTinky Winky would request Wario to make the Wa-Machine 2.0, thus giving Warui further access into Tinky Winky powers, because you see, Warui doesn't magically make stuff more powerful for people's benefit, Warui uses parts of the user's soul for Plotholium mining, slowly destroying them over time for Warui's benefit, after their soul is destroyed Warui takes over the husk and mimics their behavior, and uses them to try and throw people into the Wa-Machine. If a husk proves ineffective at serving Warui they commit suicide. The more Warui you have inside you and the more time he's been draining your soul, the less control you have. That's how Warui lures people into the trap. The only way to stop warui from doing this is to remove completely Warui from your body, thankfully the Wa-Machine has an option to do that. Alternatively the Negative Zone can be applied, as the effect renders 3.333% possession level makes Warui's grip useless, which is why Light Clones and Dark Clones aren't particularly special in terms of power.
Now you may be wondering what happens when someone uses the Wa-Machine for cloning purposes, the answer is that the soul is split in twain for both bodies and, without excessive splitting will recover over time on both sides, with Warui expending some of it's own power to make things seem normal some of the time. Death from cloning abuse can be seen in some of King Frost's Jack Frost subjects, as the soul would be too weak and Warui knows helping them would be a waste.
WaTinky Winky Project[]
WaTinky Winky, the first of many in this lineage.
Since Warui has no body, it has to manipulate others to make one for him. Which is why Tinky Winky was the perfect candidate for this, as Tinky Winky is already the most powerful of the Teletubbies, and nobody would suspect a thing, right? It's just Tinky Winky being evil after all. So Tinky Winky started getting thrown into the Wa-Machine over and over again, until more powerful Wa-Machines had to be made that could do even more Wa and extract more Tinky Winky Essence or whatever. There's so many of these guys now that you can just skip to the conclusion at The Wa-est version of Tinky Winky.
During the end and beyond...[]
The records this far out into the future are a bit murky, but it's believed that during the final breaths of the UnOmniverse that Warui either made a perfect Wa-Tinky Winky, or a Wa-Clone of Chuck Norris, and that for whatever actually happened, Warui sucked up all its power and became very very powerful, leaving WaChuck Norris weak in the process. After this point, it's said that Warui would go on to permanently wa-ify other cosmic horrors like Gorefield and Giygas and go on a rampage killing or wa-ify a lot of other gods, cementing himself as the one true god, much to God's amusement. At the end of it all, Warui got killed by WaChuck Norris after he poked Warui's true form, causing every Wa-Guy that was still in existence to to disintegrate (which included Warui).