Isaac is the game's protagonist, aka The Hero
. His personality is essentially nonexistent
, except for the little bit that's conveyed in the answers you give to the Yes/No questions throughout the game. If you answer mostly Yes, then Isaac is a brave, honest, and idealistic fellow, but occasionally a reckless and not necessarily very smart. If you tend to answer No, then Isaac is a bit less brave, much more realistic, and much more cautious young man. Note that that's just a generalization of the results from any question, as it's occasionally reversed.
In terms of combat mechanics, he's The Mario
. His stats aren't the best among anyone in the group, but his average total stats are very good. He's easily the best party member. He has single-target healing, which is handy in a pinch, and he also learns the Revive Psynergy late in the game, which can bring a dead character back to live. His attack Psynergy is also pretty good, and he'll consistently be the best or second-best damage dealer in Golden Sun.
Garet is Isaac's best friend. In terms of the Five Man Band, Garet is the resident Big Guy
. Even when Isaac and Garet are carrying identical weapons, his will look bigger. His personality in the beginning tends to fill a much wider range, but that's mostly because he's the only other character we've got at first, and thus he needs to fulfill a few more roles. He'll settle himself down into standard Big Guy tendencies after the game gets going. He is pretty much the dumbest person on the team at any given time. In fact, his stupidity is only rivaled by the antagonists.
Speaking in terms of combat, Garet is The Brick Wall
. He's slow as molasses, almost guaranteed to go last unless you fiddle with his Djinn. He hits a bit less hard than Isaac, but he's got more HP and Defense by far. His PP will be the lowest in the group, however, and his Psynergy attacks aren't as good as Isaac's. He also lacks healing Psynergy. Because he can absorb hits so easily, he's handy for carrying the healing items and the Water of Life items (to raise downed allies) and for straight up attacking.
Ivan is the young ward of Master Hammet, ruler of Kalay. Encountered in Vault where we helped him recover his master's rod
, he fills the group's role of The Smart Guy
. He's the youngest member of the group, and yet in many ways the most mature. He's also kind of a buzzkill. Generally, he'll be the member of the group deducing things and talking a lot. He still wants to save Hammet from the clutches of Dodonpa, but that won't be happening for a while.
Combat-wise, Ivan is The Squishy Wizard
. He's got the most powerful Psynergy most of the time, but his melee attacks are usually terrible and he bruises like a banana. He's got all the PP he needs to never have to worry about physically attacking if you don't want to. He does have really high Luck, which means that he's very likely to trigger special weapon attacks, so at least he's not a total melee washout.
Mia is the eldest remaining disciple of the Mercury Clan, a group of healers who live in Imil and defend Mercury Lighthouse. We find her in the midst of a terrible outbreak of the flu, and work with her to try to stop Team Jerkface from lighting Mercury Lighthouse. When we ultimately fail, she joins the group as our resident female
. Occasionally, she picks up some of Ivan's Smart Guy slack, which I find utterly insulting as she, like Ivan, knows nothing about her particular power until we meet her, whereas Isaac and Garet have known all about Psynergy for years. But I digress. She seems to either be related to Alex, the most fabulous
member of Team Jerkface, or to have been intimate with him at some point. Point is, they were close.
In terms of battling, she's pretty much (you guessed it) The Staff Chick
and The Medic
. She's about as squishy as Ivan (maybe a bit less) but with a little more HP to play around with. Instead of Ivan's powerful offensive spells, however, she's packing the most potent healing the group has. Her physical attacks are a little better than Ivan's in their default classes, but she's still a distant third to Isaac and Garet. She's there to heal, and that's about it.