If a creature is transformed into another creature (say, a human into a dog), then that creature will become more and more accustomed to the new form until a point is reached where reversing the spell is impossible. A second transformation is possible, but the creature will have to go through the whole process again.
An ancient, psuedo-immortal race has been manipulating something important (politics, religion, economics, etc.) for centuries. Hardly anyone is aware of them, let alone their goals.
Young kid from last town has been following the PCs and doing a rather good job at it. PCs weren't expecting to be followed so weren't worried and the boy/girl was careful. Notice the follower a couple days out of town, kid ran out of food and started getting careless. Followed the 'mighty adventurers' to see if he could join them. Father is a wealthy merchant. Bring him home, bring him with, send him off? What do you do with an unwelcomed guest.