Day 5; Favorite recurring NPC
Hands down would have to be the grimalkin cleric.
Someone linked me that particular homebrew race, and I was eager to make one but already had a decently full roster and no room for a new game to test such a character in. The perfect opportunity came up in a game I DM for on Monday nights when the person behind the party's cleric had to take a leave of absence due to his job and wouldn't be able to attend for what he thought at the time might be a few months. But since this was intended to be a long-term campaign I told him I'd write his character out in a way that would allow him to come back if his life circumstances allowed him to come back before we were done.
By this point the party had already defeated a necromancer, but one in the party had expressed he wanted to do some out of game stuff that would only involve his character so as to avoid wasting time during the actual campaign. I said sure, and in a twist I didn't see coming he pulled some stunts and revived the necromancer. Because the party did not question her before attacking, they simply rushed into the combat and killed her. But this guy wanted to know her motivations, wanted to know if there was a way for her to seek redemption.
So I pulled a few strings myself and had a very well-established powerful entity step in. She changed the human into a grimalkin, and her necromatic powers into healing powers. A way to give this player what he wanted and replace our missing cleric so the party didn't have to worry about stocking up on extra potions and wasting turns during combat to disengage and run and down healing potions and repeat.
The cleric was only absent for 3 sessions, however, and then was able to come back. With no need for the cleric cat and with the player who wanted her returned sadly turning out to be a rules lawyer and having to be kicked from the game for arguing with and picking on other players (among numerous other things) I wrote in his death and the disappearance of the cat as she disliked the party anyway and was now no longer bound to the party member in question.
But as fate would have it a few sessions later some events happened that the cleric simply could not reconcile. The player behind him felt it was only right to retire the character from their current mission given his emotional involvement in the matter and made a witch character in the black magic school, opting not to take white magic and continue to be the party healer. So a bit later in that same session I reintroduced the cleric cat and it was funny to watch half the party be relieved because they know she can't hurt them based on bindings from the being that turned her into a cat in the first place and the other half wanted to shoot and skin her on sight because they had figured out her true identity.
So she's back with the party, making her a recurring NPC, and in the event she's no longer needed I can take her out and bring her in as needed. I'm also probably going to keep her in general for other games where I am the DM, as I feel in most cases if the party lacks a cleric I can use her to help out :)