An insane crossover theory regarding Shaiapouf.
Pouf is (partially) Yaminade no Itsuki, more or less, who, while weakening from dying of starvation, accidentally fell out of the Ura-otoko as his interdimensional powers weakened over the Hunterverse, and he and Sensui's corpse were eaten by the Chimera Ant Queen [her mistaking Itsuki for a Nen-carrying human, and also deciding not to let Sensui’s corpse go to waste because she could have sensed it was a "rare" human].
Sensui's body became part of the King (along with thousands of other powerful humans- which would explain why the Ant King is a combo breaker), Itsuki kind of lost his conscious memory after being mixed with butterfly DNA and becoming an ant/Pouf, and could only subconsciously sense Sensui's presence in the King, not knowing due to memory loss/ant-ification he was technically looking in the wrong place for his boyfriend- Chrollo has Sensui's SOUL, which somehow slipped out earlier- and also became more unstable/yandere because of the process, either because he’d been losing it inside the Ura-otoko, because of his memory loss, or because there’s a third creature (possibly 100% human) Pouf got his DNA from. Or because the creature that he kind of unconsciously senses his former boyfriend in would be acting fairly out of character for Sensui , going after Komugi (and he can’t sense the other people in there or quite get that the King isn’t Sensui).
Proof, you ask?
Shaiapouf and Itsuki have very similar body language and expressions (just showed two here, but there’s a lot more overlap-anyone familiar with YYH and HxH care to help?).
Their abilities can be both interpreted as Reality Warper properties- Pouf’s mind control (an ability Itsuki would have relished having, BTW) and ability to manipulate his body to look like someone else’s/Beelzebub, and Itsuki’s control over dimensions and his shadow hands ( a similar extension of his body to Pouf’s clones). Oh, and can’t forget the eerily similar motives- extreme devotion to one man and his insane cause. [In Pouf’s case, more than ant instinct can account for- he wants to murder Komugi so that the king can concentrate on him.]
Add to that that people in the YYH-verse never knew where exactly Itsuki and Sensui ended up, and you’ve got yourself a perfect storm for a possible inter-Togashi-series crossover. (I do realize that Itsuki isn’t human, but- as I said earlier- the inhabitants of the Hunterverse (the narrator included) may not have realized that.)
So...ummm... forgive my loony conjectures. Have fun!!!