Well, perhaps further plot knowledge will assist. I'm sure you've already read this, but I'll summarize:
Renault is the ever zealous military commander, with an excellent sense of right, wrong, and moral code. However, since war has not been a fact for centuries, his actual power is restrained and his involvement small. His post mainly is responsible for keeping the physical arm of the Vanguard fit, and little else nowadays; since Luther and Pierre hold more real world power, Renault is somewhat of a pawn, who controlled, can influence the soldiers. However, this is not implying he's stupid; he's simply in a position of reduced power and the work of his men is currently at the disposal of Luther or Pierre. His conflict will chiefly be with Luther. When Luther creates a catastrophe just to justify retrieving the Masamune, Renault's going to try and fight him.
Luther is the PR guy, but is a bit of a serpent. He has little care for the Vanguard's actual image, as long as the soldiers are under his thumb. A vain person, he mainly enjoys soaking up the image, appearing at the castle and carrying out projects for mostly his own personal gain. While he holds little regard for the ideals of the Vanguard, and could care less about who this "Glenn" or something guy is, but he is particularly interested in the supposed treasures lying underneath the building. He's especially curious about the Masamune, as he'd love to share in its luster by owning it one day. In his dealings with others, he shows a certain degree of tact, but it erodes arithmetically with the duration of the conversation. He hates being derided intellectually by Pierre, and seeks to avoid him whenever possible. Likewise, he pokes fun at Renault often, simply because Renault's good standing allows him to take the abuse and dismiss Luther. Eventually, Luther will create a catastrophe conspiring with Porre to retrieve the Masamune.
Pierre is the brains of the outfit; a longtime examiner of history, the arts, and other worldly subjects, he brings positive practicality to the table (though his love of books has sapped his taste for action). Born with a quick mind, he's able to turn a pithy phrase in arguments or retorts and manage to defeat his opponents in debate (and anger them as well). Regardless, his experience and knowledge has given him a full belief in the ideals of the Vanguard, especially in the past few years, as he sports a particular distate for Porre's rude insurgencies. While he recognizes that Porre can be controlled, given half the chance (and some disorienting drink), he'd gladly orchestrate a chain of events to humble the nation into recognizing its parent kingdom publicly (not militarily).
Pierre recognizes that Porre's main beef is that the Kingdom of Guardia is tying up the world's wealth in a defunct, stolid, and stagnant organization, and that splitting the kingdom and its dated laws would provide several nations with the freedom to mobilize their own research, social structures, and advancement. Pierre might have subscribed to this belief had he not had utmost confidence in the Kingdom of Guardia, doubly reinforced by Crono's introduction to the royal family. Pierre believes the sort of enlightened despotism of a single kingdom and ruling body acts as a catalyst to human advancement, provided the rulers are in good form and some kind of council exists to check one another. He also knows that fragmenting Guardia at this point in scientific research and fomentation would set the world back several years, despite the freedom, and holds that social evolution will take place regardless of whether Guardia splits or not in the future.
Pierre will offer the party advice and try to keep them in line, and will also offer the important plot above.
Can we think of better names given that information?
