Same start town/city?

[Estellios]

As the others have been saying, play as Marauder and Arcanist. They both start in Limsa Lominsa.

Arcanist will be a perfectly capable healer until level 15, when you get your airship pass and can travel to the other cities easily. Then your son can unlock Gladiator, you can unlock Conjuror, and both of you will be set to unlock your Jobs at 30, as you will have your sub-class requirements met.

Marauder is a Tank by the way, so your son can decide if he likes Gladiator or Marauder better when they are both level 15 and just continue with that.

[MisaCeliousa]

here's how you do it. your son starts as Marauder and you as arcanist. you both lvl to 15 and take the airship to Gridania where you pick up conjurer and your son goes to Ul'dah and picks up glad, next you just go lvl together like that.

if you're wondering why you would start as another class than what you want to play in the end. at lvl 30 you'll need a lvl 15 arcanist to be able to advance your conjurer to white mage, and your son would need glad lvl 15 to become warrior

In case your son would prefer to play glad and become paladin, I'd recommend you both start as conjurer and lvl to 15 then you change to arcanist and your son to glad and both lvl together again