depends on the context, if the dragon is like the ones in this story and the iguana is a normal animal then it could be considered bestiality, if the dragon is a "normal" dragon it would be ok because both would be animals, if both are humanoids then it would be pedophilia, but like i said in the comment above the real problem lies in the girl character.if a thousand year old dragon wanna marry a 3 year old fully grown iguana, would you care? smh...