linaslencas: You must have dragon bloodline.

Erelah: There are several diffrent draconic bloodlines to choose from both colour and metallic.

decade7: Wizard, Cleric, Druid, Magus, Paladin & Ranger are prepared casters.

Sorcerer, Bard & Inquisitor are spontaneous casters.
Inquisitor won't work for you, as their spells are divine rather than arcane.

I'm not sure about alchemist, in the P&P they are a bit of a wierd exception - their Extracts are not spells but count as spells for some purposes - I doubt they would count.

So that leaves Bard & Sorcerer. As far as I know archetypes never change a caster from Divine to Arcane or from Prepared to spontaneous, so you should only have to consider the base class.

Greger: The magus archtype eldrich scion is also eligable as you switch to spontanous casting and choose a bloodline. I would argue this is infact the best choice for a Dragon diciple as Magus are the most melee focused base class caster

jimmybackman: So wanting to make a 2 handed Fighter, Dragon disciple and its not that clear exactly which classes that count as spontaneous casting, is it all sorcerer and bard subclasses or does some other caster work out too?