↜ tl;dr version about presea
I'm ashamed to say that it's been many years since I played the game, and I still have yet to get another copy, so most of what I've written here is from my vague memory of her. It will be corrected at some point, if there is something, haha.
Presea is introduced as a lumberjack delivering wood to the Meltokio Castle, and helps the group get inside to get some kind of an audience with the king. Despite her being silent most of the time and only speaks when prompted, the group helps her to return to Ozette safely, only to find her back to taking care of her father who is supposedly "ill", but the group shortly finds out that her body is being consumed by her Exsphere and is unaware of her surroundings properly. Worried about her, the party were able to create her a proper Key Crest and she's come to realization about the events and her life.
Her determination remains very strong even after having to hear all the shocking events that occured, and she dedicates her strength to help the party to save Colette and to make up for what she believes she caused to others. She joins you as a frontliner! Presea focuses on dealing massive damage and has good endurance. Only setback would be that swinging around a giant axe like that doesn't make her very quick and vulnerable to getting attacked, but she's definitely a party member to keep in battles.