I've noticed the pitou/kite tag has some clear patterns, and honestly, the grief-and-atonement angle is the one I keep coming back to. A lot of writers pick up after the... you know, the event. It's not about skipping the tragedy but exploring the impossible aftermath. Pitou, this incredibly powerful being with a childlike capacity for devotion and cruelty, now having to process what they did. I'm drawn to fics where Pitou uses their Nen to try and rebuild or repair Kite, but it's never quite right—the new body might function, but the memories or the soul are fractured. That inherent melancholy is compelling. It's less about forgiveness from Kite (who is often an amnesiac or non-verbal vessel) and more about Pitou's solitary journey through regret. The best ones don't make it easy or romantic; they make it psychologically raw.
You also get a subset of stories set before the fight, in a sort of 'what if' scenario where they meet under different circumstances. Those can be interesting, exploring a potential master-apprentice dynamic or a mutual study of strength, but they always feel a bit like fantasy to me. The core appeal, in my opinion, lies in the narrative space created by the canon's violence. It's a specific kind of angsty character study that you don't see in many other pairings from 'Hunter x Hunter'. The writing quality varies wildly, of course, but when it hits, it really lingers with you.