Hmm... aside from the BBEG Rakshasa (who wasn't a Rakshasa) who got back up after one PC nailed him with a blessed crossbow bolt on a nat 20 (the player was dancing at that moment). Look on their faces was priceless.
Otherwise I've got a PC who through various means and plain dumb luck has gotten two NPC's in their heads, not knowing how much control they may have, if they know each other are in there, and even the alignment of one of them just that he's OLD, forgotten for the most part, and rather powerful.
One of them is an Arcanoloth who's using the PC like a plaything. Alternately offering much for apparently little cost, subtley undermining them and perhaps their alignment with this tempting, and giving them tasks to perform if they want them out of their head.
The other one appears as a tall, well built, charismatic man in archaic black clothing, with little more than the lower half of his face visible. Always followed by a short, robed companion who has no features visible but has been seen once persuing a fleeing man through a field of tall grass, catching him and leaving little behind but a smear of blood on the ground after itself as it walked away. The taller one rubbed the head of the smaller one like a trained hound returned from a successful hunt.
This being refers to himself as The Jester, or The Holder of the Keys, and has strongly been hinted at as being the original builder and occupant of the The Palace of the Jester in Sigil. (likely the oldest, or one of the oldest buildings in the City of Doors, origin and true age is unknown). He may or may not even be human, or alive for that matter.
Kudos if anyone gets the tribute here to Count Magnus, a short story by M.R. James. *fiendish grin*
But both of these critters have access to a PCs mind, with varying and likely hidden agendas for him. It's driving the player batty, and they're pondering trying to play the two off of each other.
