Killua and Gon both are dating reach other after the Chimera Ant ARC. Killua promised Gon to protect him forever, Gon just thought it was the classic protecting they’ve always done for each other so he was pretty acceptance towards the promise. Killua however met it in something more deeper than merely protecting Gon the classic way.

When both boys worked as Hunters, as usual, they made more friends. Killua was jealous whenever Gon would give other people attention that isn’t KILLUA’S FRIEND (yeah, Killua only trust his own friends, and Alluka with Gon).

One of these days, Killua left Gon (something he rarely does) to go to the bathroom. When Killua got back, he saw a girl named; Kasai, flirting with HIS BOYFRIEND!

Kasai: “Gon-chan, you’re so sweet! Thank you so much! I love your hair, it’s beautiful, especially like your eyes.”

She chuckled playfully, trying to make a move on Gon. Gon was oblivious 💀

Gon: “Thank you, Kasai! You also look good!”

Gon smiled brightly, literally oblivious. But Killua’s OVERLY POSSESSIVE, JEALOUS, AND PROTECTIVE HUSBAND MODE ACTIVATED… Killua was tempted to kill the girl, he went over to Gon and forcefully grabbed Gon’s waist, pulling him closer.