Hello. This is my insane attempt at trying to explain why Wagyukiller, or Wagyu/Painkiller, is, as the kids say. Peak. At the behest of my friends who need to know how my mind works. This is also kind of a general Painkiller analysis.
It's really hard to sell Wagyukiller without selling the basic understanding of Painkiller as a character first.
The main thing to understand about Painkiller is that they have an attraction to the unknown. When things are kept vague and hidden away from them, they grow sultry in the shadows. This is most obvious with how they view Carrot: Although they know little to nothing about him other than vague ideas and idolization, they've already envisioned him as a lustful person that "screws around" and would throw himself at them given the chance.
(Keep in mind that the Carrot we see here in the second image is NOT Carrot! This is a figment that Painkiller came up with based on their own wild fantasy and obsessions.)
This shows up again when Warhammer's very existence is brought up. This is the only conversation they have about Warhammer, and Painkiller is already jumping the gun to fantasize about him, because he is unknown to them.
(It also seems to be implied that Painkiller's crush on Fossil largely started while they were talking online, as Fossil was more unknown to them then. Romance seemed to more or less be on Painkiller's mind from the moment they got on the train to High Society.)
Painkiller also very much has an incredibly addictive personality, and yearns for indulgence and luxury whenever possible. They seem to be somewhat aware of this, but romanticize and downplay it often.
This is something that comes to a head in Upper, where they harshly and immediately abuse the hallucinogenic they've made. One of the traits associated with addictive personality, other than the obvious, is thrill-seeking behavior, which Painkiller is happy to play out often. Danger seems to course a rush of adrenaline through them.
(Notice Painkiller's focus on Carrot's larger paws/claws here. Painkiller being covered in scratches throughout Upper also can imply that they've put some focus on the idea of him scratching them.)
On another note entirely... Parasites in general are interesting beings. If you sliced an object open when a parasite hasn't had time to fully assimilate them, they're probably not all bugs under there just yet. In fact, according to Fossil, objects show no sign of being infested before it all just... Bursts out. Even with Wagyu, the infestation only seems to come from his eye, sweat, and arm (when he's not further assimilated, that's another beast entirely). It's not the object. The infestation lies elsewhere and bursts out of the object. Organspace seems to be the only correct assumption. Another thing that Painkiller seems to be obsessed with.
So, this is all to say, uh. Painkiller could do with a partner. A real physical one that doesn't exist in their head.
Who do we know that...
Is generally and scientifically not understood, by himself or those around him,
Is perhaps the ultimate example of luxury and indulgence,
Is incredibly dangerous,
AND is just FULL of weirdness going on in organspace?
That's Right. That's Right!!!!!!!!!
I don't think Wagyu and Painkiller would necessarily be able to have a healthy standard relationship and I'm not even sure if Wagyu would necessarily return the affection, but there's a universe somewhere where Painkiller keeps Wagyu in that glass chamber in Fossil's lab and falls in love with him. The distance, the fact they can never truly touch, this makes them want him more. The danger is attractive to them, a constant song from within. Until they break that barrier, they can never truly know Wagyu, even if they study every inch of him, and that's the nail in the coffin for their poor little heart. And I'll be damned if I don't love doomed relationships.
BONUS: When Wagyu's ego is high, he tends to talk in a more flowery and regal tone.
This kind of tone seems to be something Painkiller actively fantasizes about.
