Maybe the spell is a transformation spell. The 'penis' could be a symbol in the spell incantation, and when cast on Dean, it turns him into something that is related to that symbol in a very strange Supernatural way. Like he turns into a mythical creature that is associated with male - ness or fertility in some way.
The spell could be a joke spell. For instance, it might make Dean say the word 'penis' every time he tries to cast a real spell, creating a humorous situation. It could be used to lighten the mood in a tense Supernatural story.
It could be about a spell in the Supernatural world that has some strange or comical effect on Dean related to the word 'penis'. Maybe it's a misfired spell that gives him some sort of embarrassing situation involving that body part in the context of the show's supernatural elements.
One common theme is Dean's loyalty. Fanfictions often highlight his unwavering loyalty to his family, especially Sam. For example, in many stories, he'll go to great lengths to protect Sam from any danger.
One great 'Supernatural' Dean fanfiction is 'A Different Kind of Monster'. It delves into Dean's internal struggles in a really interesting way. The author does an amazing job of capturing his character traits.
Well, it could be about a character having a strange penis that gives them some sort of unique power in the Supernatural universe. Maybe it glows and can repel demons.
In fanfiction, when Dean becomes a Prince of Hell, his personality could shift. He may start to see things from a more demonic perspective. His relationships with other characters would be redefined. For example, his bond with his brother Sam could be strained as Sam tries to save Dean from his new, dark self.
Well, in some fanfictions, Dean as a Knight of Hell has enhanced physical abilities. He can be faster, stronger, and more resilient. This makes him a formidable force in battles against both demons and other supernatural creatures.
Some fans speculate that it's a setup for a major character arc transformation. They think that his disappearance will lead to him coming back stronger and with new powers or knowledge. For instance, he might encounter some long - lost angels or a new type of hunter who will teach him unique skills.
The mirror can also be a symbol of truth in Supernatural fanfiction. It shows things as they really are, even if the characters don't want to see it. So, if there's a spell or a mystery involved, the mirror might be the key to revealing what's really going on. Maybe it reflects the true identity of a shapeshifter or shows the location of a hidden supernatural object.
Maybe Dean gets cursed by a witch. The tail could be a side - effect of the curse that slowly changes him. He has to find a way to break the curse while still hunting monsters, and Sam has to deal with his brother's new 'accessory' and the problems it causes during their hunts.
In this 'dean becomes a dragon supernatural fanfiction', it could start with Dean being in a fight with a powerful demon. During the battle, the demon casts a spell that backfires and instead of killing Dean, it turns him into a dragon. Dean then has to deal with the fact that he is no longer fully human. He may have to hide from other hunters who might see him as a threat. Meanwhile, he tries to figure out how to use his new dragon abilities to continue his fight against the supernatural, all while trying to find a way to turn back to his normal self.