Eleanor Rigby

Killua wants to see Gon.
He wants to see him tied to a chair; ropes tight around his neck and ankles and dripping blood, and he wants to stare at him until his eyes water up and all he can think of is Gon.

Sometimes, that's what Killua wants.

During the daytime, (when he's with Gon), Killua pushes these thoughts to the back of his mind and pretends like they aren't there at all, and he feels perfectly fine.
And then Gon will look at him with a smile like headlights and says something ridiculously cheesy and too nice, and Killua is happy.

But there are times.

There are times when Killua is supposed to share - when there are others with them and Gon turns away and flashes his headlights smile to somebody else, and for a second Killua feels an indescribably dark, inky rage twisting in his stomach; and he remembers.

One night, when they're having dinner with Kurapika and Leorio and Alluka, it occurs to him how nice it would be to hear Gon scream his name, eyes shut in pain as Killua slides a knife across his face with a smile. And then he forgets about that quickly, but adds it to his mental box of Things To Poke At Later.

Hours later, he lies in bed (not quite asleep, but not completely awake either) and thinks about it. When he opens his eyes, there's darkness; and he closes his eyes again before they can adjust. He can't hear Gon's cries but he can picture them, and he can see his brother's face too, saying I Told You So with that unreadable look that Killua absolutely hates and has never understood.

He goes to sleep (for real this time) and forgets about it (for now).

Nearly three weeks later, Killua asks Kurapika just how he'd gone about killing Uvogin all those months ago, and Kurapika makes this face like he's going to be sick (and maybe he is, Killua thinks) and then tells him exactly that. Kurapika describes the feeling of having blood on his hands for the first time (as if Killua doesn't already know) and how he never, ever wants to feel that way again, revenge be damned.
Killua is reminded of how boring Educational Parent Talks are and regrets asking Kurapika in the first place.
It's not until Gon is by his side again that he forces himself to actually consider those words, when the temptation is too much.

Killua wakes up too early the next morning, so he pulls the knife out from under his pillow and pushes it through his index finger because he can and thinks of Gon. The blood drips onto his shirt and blossoms into an ugly brown flower. Killua licks it off.

When the feeling comes again, it takes all his strength to ignore it. Beside him, Alluka closes her eyes and Nanika wakes up, and Killua smiles.
Once they're finished, he won't have to think about those things again. He won't remember them.

"Killua, pet me." says Nanika.

"Sure," Killua replies.