[@Shoryu Magami]

Yeah, we talked about it a bit. The way I see it, Ritz and Marche can unlock classes from characters they get to know; For Ritz, it's more about befriending, and for Marche, it's more of a kind of respect thing, I suppose. Marche, once Cecil begins to actually talk with him, will over time unlock his paladin class; And possibly, if he actually does change sides, a new EX-MODE based on it. His current EX-MODE could be considered a class obtained from Mateus; Though Marche was forcibly given this power, so it's not the same thing.

The only other Chaos member that Marche will probably gain is Thief from Zidane; Considering they are just two dudes in a hell of a mess. Aside from that, there's not a lot of potential candidates for giving Marche classes past that unless he changes sides; In which I'd say that Kain, Galuf, and perhaps in some odd way Layle could have an effect on him. Granting him Dragoon, Samurai, and some new type of possible class based off of Layle's crystal bearer style. 

As for Ritz, she will most likely develop a stronger Magic class due to Terra; And may find herself improving from Layle as well, with other possibilities being limited. Perhaps Firion, in some way. Since she's a bit of a hybrid fighter, she could learn more minor physical combat classes, one of which he might be able to offer.

Perhaps in a moment of pure irony, while Cecil allows for Marche to access Paladin skills, Ritz ends up gaining something more from the Dark Knight spectrum. This is all, as of now, speculation; As I don't know if any bonds will possibly be strong enough to cause these reactions until later on in the story.