"I want to play a dragon!"
These are words every GM has heard at one point or another. It's almost always followed by "Well, they're really not meant for play by characters...."
I don't know about you, but I never like giving that answer to people. So I've come up with a better one. It goes a little like this "So you want to play a dragon..."
Ranger 4/Sorcerer 1/ Dragon Disciple 2
So we start with a ranger. "But Research," you say, "Rangers aren't arcane casters, why would you use them for a dragon disciple!?" Because I'm building a Dragon, not a dragon disciple! First level is pretty basic. Little bit of flavor in the human feat: Fey foundling (PFCS 81) giving you a little bonus to your wild empathy and a little DR/Cold Iron. You'd be surprised how handy DR 1 is. Downside? Cold iron weapons do an extra point of damage to you.
First level feat is power attack. Why? Because power attack is really, really good. It opens doors, too. Also pick up track, wild empathy, and a favored enemy. If you're going into society play, I recommend Humanoid (Human). Otherwise, favored enemy Fey is also a good one.
Second level of ranger gives you combat styles, and we take natural weapon combat style. This opens up aspect of the beast (Read the special rules for the feat at the bottom of its entry), giving you claws. Can't disarm you now, and two claw attacks are rather draconic.
Third level gets us cleave and the shapeshifter variant class for the ranger (APG 126), taking form of the dragon for some major AC bumpage when it counts.
Fourth level of ranger brings us to "spells". Well, we can't cast spells with a low wisdom, so let's take skirmisher. Ranger spells aren't inherently amazing for this character anyway, and mixing arcane and divine spells is a bookkeeping nightmare. Skirmisher doesn't come online until ranger level 5, but you lose nothing for it. You also get an animal companion of some kind or a nature's bond for your friends. Depending on what you're working with, animal companions can get pretty awesome, but this character doesn't need one to work out.
5th level is when we really get draconic. First level of draconic bloodline sorcerer. Pick some spells, doesn't really matter which ones. What's important is draconic claws, and the access to great cleave.
6th level we're finally in Dragon Disciple levels and man does it feel good. Blood of dragons means your draconic bloodline continues to increase as if you kept taking levels of sorcerer. A little natural armor increase helps too. Finally, that d12 hit die really helps offset the loss of HP on the d6 from the sorcerer level.
7th level gives us access to a bite attack a few times a day when we're working with draconic claw rounds, and we also take Improved Natural Attack (Claw) to get us a die size increase. This is important because enlarge effects are all kinds of good for this character. We also get a bloodline feat, and I recommend Toughness. Dragon disciples are a tank, and they draw a lot of fire. Good thing we get draconic resistances from the bloodline at this level and
Easy feat progression breakdown:
H - Fey Foundling
1 - Power Attack
2 - Aspect of the Beast
3 - Cleave
5 - Great Cleave
7 - Improved Natural Attack (Claw)
Let's examine the character at seven.
Fort: +5 + Con
Ref: +5 + Dex
Will: +4 + Wis
AC: 12 + Dex + shields + armor
Which puts us almost in line with monk defenses except on the AC front, and a quick breastplate and shield ensemble fix that. Like a dragon, we're weak on the touch AC, and that stays on flavor so I'm ok with that
What's important to remember is all three attacks (Claw/claw/bite) are on full BAB! that's HUGE. 5-6 rounds/day you've got 3 attacks a round at full BAB before haste. At level 7. That's insane. Fighters usually only GET 5 or 6 full attacks per day.
GM Note: I would always consider the draconic bite a two-handed weapon. It gets 1 and 1/2 strength and you can use it limited amounts per day. If someone were to take furious focus and the like I'd let it apply.
The character qualifies for spells as a 2nd level sorcerer, but due to magical knack casts them as if 3rd level. (This is a sticky ruling even I'm not sure on. See disclaimer)
Magical Knack Disclaimer: NOT LEGAL in society play. This thing is a sticky talent. It boosts caster level by two, up to your HD. The question in play is does it grant access to spells. Practiced spellcaster specifically stated that it did not grant access to spells, knack doesn't clarify that. I doubt it's meant to give access to them.