As an artist, I feel the problems start since I sell prints and art packs, and commissioners agree I can do this with the artwork when they fill out my TOS agreement form, but with 'surprise' commissions, I find I don't have every participates agreement and can't use the artwork. What if the other character disagrees with my TOS? It's been a strange grey area. Also, it's been a growing problem of people using other's characters without permission in pictures that the owner doesn't agree with. I feel this protect people better, and protect me from being in the wraith of a person who I accidentally helped harm.
For a long time, I've felt uncomfortable doing people's characters in paid work without the express permission as a 'surprise' gift for the person from the commissioner. Am I in the right for not allowing it anymore? Am I being too harsh?