Killua thought that the worst thing to have ever happened to him was being turned into a vampire and maybe, maybe, that he kept it a secret.
The list was being rapidly updated.
First someone started stalking him and Gon, then he stopped being able to feed, not wanting his secret to be exposed to the stalker, then Gon started asking questions about why he looked so miserable and weakened all the time—
And then someone, probably the stalker, had the gall to attack them.
It was a Nen-user, a vicious beast that parried all their attacks with a nonchalance that spoke of years of training. A fellow assassin, maybe. He didn't speak, didn't boast, just slashed and punched, and pulled, and kicked until Killua, in his weakened state, ended up lying flat on his back, dark spots dancing in his vision, and dizziness not letting him immediately get up.
The stranger, of course, used it to his advantage.
Immediately he went for a finishing blow with his knife… but the attack never came.
Killua watched with wide eyes as Gon, like in slow motion, pushed himself on the path of the knife and it sank into his body with a sickening quench.
Now, normally Killua wouldn't be pleased, to say the least. But logically he knew that Gon had a higher chance of surviving a knife to the stomach as an Enhancer with a stronger body.
But at that moment something in him broke. The slowed-down state he found himself in grew as he rose from the ground and ran into the attacker, knocking him down. He didn't know where the speed came from, nor the energy, but he wasn't complaining. No, all he was thinking at that moment was red-blinding rage. How dare he hurt Killua's Gon, how dare he hurt his best friend, his soulmate, his—
He tore into the attacker with his sharpened nails, tearing through his Nen-enhanced clothing like it was nothing more than a simple cloth. With supernatural strength he tore into the man's chest, and in one swift motion ripped out his beating heart.
He expected a wave of hunger to overcome him at the smell of blood, since the beginning of the fight, but at that moment the only thing he felt was rage as he stared down at the organ in his fist. The wound wasn't pretty, not like he was used to removing the heart carefully, but simply a torn out hole with visible cracked ribs.
The hunger did eventually come though, creeping in slowly and whispering to him that he could eat the heart, that it wouldn't make him nauseous like other solid food. And he was angry, so angry at the attacker— The whispers were effective. He took a messy bite and moaned at the taste, then another, and another, until the heart was gone. Only then he took the body's arm and brought its wrist to his mouth, he drank the cooling blood greedily, letting it fill his stomach and energise him.
But as he drank his mind became a little clearer, even if not fully. Gon. Gon, he had to check up on Gon.
He released the arm, and turned to his friend, his only, his. A worried purr raised in his chest seeing Gon just standing there with a knife in his stomach. They both learned how to heal wounds like that ages ago, he should be doing that, not just standing there, watching— Oh. Watching him. Watching him… being a beast. Oh. Oh no.
"Killua…? What— What did you just do?" He sounded accusing. He sounded scared. He sounded disgusted.
Killua blanched.
"What did you do?" the question repeated, a new emotion picking through the other ones on Gon's face—anger.
Killua got up.
And he fled.