Okay, so I ran another rollicking session of my "Cauldron 7" Pathfinder game (using the old Shackled City adventure path) last night and was able to resolve a very challenging character growth situation (pun intended, you'll see).
One of the characters is a ranger with the shapeshifter archetype, with a focus on a bear form. The character, Tuli, started out just being able to transform her hands into bear claws. But for fun we worked out that she would also transform into a bear during the full moon, lycanthrope style. Now, because I'm a bit lazy I have the game set in the handy Pathfinder game world of Golarion and that world has a chaotic evil goddess called Lamashtu, Mother of Monsters. Naturally, when Tuli revealed her ability to transform the other characters were suspicious that she was either a were-bear or somehow tainted by Lamashtu. The party's paladin confirmed for all that she was not evil, even when transformed. So they were okay with it--despite the problems of corralling an adventurous (and often amorous) she-bear in town when the moon was full.
So far so good through level 5. Then we decided to change the level progression from slow to medium to better align with the adventure path difficulty and so I just gave everyone about a level and a half's worth of XP and told them to level up to 7. But then Tuli's player (Kirk, who does the great journal entries for Katherine from our Castles & Crusades game) decided to try out the summoner class and add two levels of that.
Well, the summoner class calls first and foremost for the character to have a large eidolon, or "pocket monster". The summoner also gets a lot of related summoning and augmentation spells. So how to suddenly add an eidolon and arcane spell-casting to a ranger-bear? It was a very abrupt shift in direction.
I decided to play up the Lamashtu idea and posit that Tuli was indeed "tainted" and so invented the Scent of Lamashtu. The Scent of Lamashtu means that the goddess has a hold on a mortal rather like a demon having a contract on a mortal's soul. Usually a mortal voluntarily takes it on, but it can become hereditary as well. The mortal will become more and more beast-like, transforming fully or partially at various times, and eventually permanently stay in beast form--unless they fulfill certain conditions laid down by the goddess.
In the adventure path the characters had just met a shady NPC called Kaurophon. This person is human-looking but also half demon. He has been following events in the region and approaches the party to help him with a dangerous but mutually advantageous quest. I noticed that the NPC does arcane magic and has a way of traveling to other planes. Luckily for me Tuli decided to seek Kaurophon's help learning how to summon monsters (in order to start introducing the new summoner class abilities).
Kaurophon quickly suspected that Tuli had the Scent of Lamashtu. He used his plane travel ability to take her to visit Lamashtu's plane. There a massive hyena avatar of Lamashtu explained to Tuli that she must mate before the next full moon or she would take on her bear form permanently. This put Tuli in a quandry because she had only 23 days to the next full moon but didn't want to literally mate with just anyone.
She convinced the party to return to the main city of Cauldron, where she looked up a young cleric who had shown interest in her earlier. Ironically he was a cleric of Iomedae, a crusading Lawful Good goddess--but Tuli decided to leave full explanations for later. After a hastily arranged romantic dinner at the party's rented house in Cauldron (the rest of the party away relaxing at the bath house they owned), Tuli got a rather nice mating, thanks for asking.
In the morning she had some nausea and by 9 o'clock was already "showing". They sent for a midwife as her belly continued to swell. But to avoid too much attention Tuli went into a small room with a fountain in a rehabbed bit of dungeon beneath the bath house. There she gave birth a little after noon to a lovely little bear cub with white fur (the eidolon's form). The midwife freaked out and ran off and the two female party members attending were very much confused. Most of the party is still very confused about the whole baby bear event--especially because it can talk. The tiny newborn cub quickly grew to over 200 pounds in about a day and they were off on their next adventure.