Hello everyone! 

I have a PC who would like to be a dragon in an upcoming campaign, I had an idea on how to deal with this, but I just wanted to put it out there to see if anyone had any other better ideas. 

So a little backstory on my campaign, there is a large country that is ruled by a council that took power after the revolution, no one really knows where they came from but they quickly took control of the country after the dust settled. What the people (and PCs) don't know is that the council is actually a collection of metallic dragons. They're an ancient group that saw the destruction the previous rulers caused when they ruled the country, so they decided that it would be a good idea to take over and run the country as their own. 

So back to my PC, I was thinking that he actually could've been in the order of dragons that took over the rule of the country, but since he will be playing an evil character, his ideas on how to run the country differed greatly from the others. So they basically cast him out, forbidding him to show his dragon form or speak of the council and their activities. I'm not sure what I could come up with as far as what would hold him to that agreement, some sort of pact or something maybe?

Let me know what you guys think! Thanks in advance!

Well if you consider that the dragons most likely came with there own children and kin the pc could be a wyrming or young dragon using a magic item (a ring / necklace with True Polymorph) or at one time had True Polymorph cast on him/ her for the full duration so that they could take a humanoid form (until the spell is dispelled, death and ko do not apply). To keep from being Game Breaking I suggest the second one; this may also mean that it humanoid stats and dragon stats are different. Regardless level up and refer to classes as normal; something tells me your player wants to be a magic user LOL. 

Yeah.... Having a dragon where the rest of the party is humanoids kind of outshines them and puts the focus on the dragon. Even if you try to avoid it, something tells me they'll be a little jealous. I don't think 5E has the Baleful Polymorph spell, but you could homebrew a version of that spell into your campaign, and claim the council of dragons cast it on him for having a different point of view, tried to rebel, etc., and they changed him into some sort of humanoid as punishment. The spell can only be reversed by whatever criteria you set forth, or just a Remove Curse either at it's base level or one that must be cast at a higher caster level to "overwhelm" the dragon's magic.

Black Dragon Codex.  I don't remember who wrote it, but one of the main characters is a dragon stuck in human form. 

I would basically have the player roll as a Dragonborn, but have the physical appearance of what ever other humanoid. Maybe only the eyes being some kind of giveaway as to the characters true nature... well... that and the resistance/breathweapon... also, it's making me giggle to think of a halfling vomiting acid on monsters for the first time.

Once a spell caster can turn into a dragon is a good time to allow the PC to be a dragon. Though try and see what the PCs goals are. 

I know I would end up saying no and recommend playing a dragonborn. 

Unless of course you guys can work on something that isn't going to be overpowering. 

I guess the guy took "always be yourself unless you can be a dragon then always be a dragon" too literally :) I think polymorph spell solution makes player feel cheated by you, while letting him playing a dragon for sure breaks the balance and will be unfair for other players. In my opinion it's not a coincidence you don't have a dragon race choice in playershandbook and playing a dragon is insane concept for me. Therefore I would suggest the player character has mental flaw which makes him believe he is a dragon :)

Like a lot of others here I would just reimage a dragonborn. Same stats but a dragon shape instead of humanoid. Maybe stagger some benefits. Like fire breath at 1st level, 30ft fly at 3rd and a weak fear aura at 5th. The disadvantage of being a dragon (no humanoid shape/hands, locals fear it, etc) should out weigh the slight power bump. 

For myself, I wouldn't allow it. I prefer to run more traditional games. but everyone is different. 

The main problem is how slowly dragons age, IMO. For dragons, age is equivalent to how powerful they are, so depending on how long your campaign is a dragon PC is either way too OP at the beginning or they're too young to be effective at the higher levels. Here's a chart that tells you how dragons age: http://forgottenrealms.wikia.com/wiki/Dragon_aging. Because dragons maintain their abilities even when shaped as a humanoid, there's no way one would be able to blend into a low-level party.

Quote from erikaflarsen >>

The main problem is how slowly dragons age, IMO. For dragons, age is equivalent to how powerful they are, so depending on how long your campaign is a dragon PC is either way too OP at the beginning or they're too young to be effective at the higher levels. Here's a chart that tells you how dragons age: http://forgottenrealms.wikia.com/wiki/Dragon_aging. Because dragons maintain their abilities even when shaped as a humanoid, there's no way one would be able to blend into a low-level party.