Downplayed: Tales of Troperion has three characters to choose from. Each are the same person but with a different upbringing that justifies the difference in class. The other possible classes are never mentioned directly, but there are hints of how they may have come about dropped in the game.
Tales of Troperion has three stories, each taking place in a different part of the game world. You can play only one story at a time. Each story has a different protagonist. Rex, Lady Velvet, and Swift are those protagonists.
They are reincarnations of some powerful ancient hero, so only one is to be born in this world.
The tutorial level involves breaking out of prison via a Death Course, and there's no way to help the other two, who invariably die. The end of the game guilts you into starting over and giving the others a chance to escape this time.
Inverted: Tales of Troperion boasts a Cast of Snowflakes; the only character who doesn't have a complex backstory and isn't constantly referenced and name-dropped is the hero.
Parodied: "Go ahead and choose a character to start playing. Although they all have different abilities, they do the same things, just with different names."
Rex is actually motivated by his yearning for Lady Velvet, and a major subplot in his scenario revolves around winning her heart. However, Lady Velvet's scenario only gives him a passing mention or two. Swift's story is completely disconnected from either of the others, save for an optional mission where they can swipe some plot-related trinkets from her manor and potentially end up fighting one or both of them.
The other two characters never appear in selected player character's storyline. But beat the game with all three characters will unlock fourth storyline where all of them appear, and reveal how each of them come from alternate timeline.
Rex, Lady Velvet and Swift are all adventuring together; the player's decision at the start of the game simply determines which of their plot arcs becomes the driving force of the story, along with which Side Quests and such are available.
Alternately, while the player may choose to play as only Rex, Velvet, or Swift exclusively, the other two become NPCs whose stories still go on in the background, and who occasionally interact with the player's character.
While they may never meet each other, hints of the other characters' existence can be found throughout the game, from NPCs mentioning them to signs of their actions and whether or not they're succeeding in their own quests.
The character is created by the player from an a la carte selection of class, race, gender and backstory; there's never any implication that the options not picked are "real characters".
Enforced: Adding more main characters is a standard way to add replayability to a game.
Every situation where another character would excel at is pointed out. "Now, Rex if you could disguise yourself as a guard we could just walk right into the castle. Its too bad you will never master that technique."
An NPC constantly gets the chosen character's name confused with another one.
Defied: Those knight talents might be hard for a wizard to get, but it really helps against those magic immune NPCs.
Discussed: BigBad: "I've gone over all the calculations, only a wizard, knight, or thief could have survived that accident." I've prepared for all 3 just in case.
Conversed: "You know, what happened to those other characters I didn't choose? Did they just disappear or something?"
BigBad: "Ah, a knight, let me call up my wizard, he should be a good test of your abilities. Pay no attention to the side room of traps, that's for other guests...not that there has or will be any others."
Reconstructed: "...It's too bad the room won't get any use. It's really quite interesting, and I've even baited it with a nice trophy that transcends space and time."
Plotted A Good Waste: The dialog in the game is identical for every character. Even situations where the powers of one character's power might be used to get past the plot are simply ignored.
Played For Laughs: On the character selection screen, each of the trio encourages the player to pick them by boasting about their skills and playfully insulting the others. When you finally pick one, the other two throw down their weapons and complain.