In Mythe's Scenario, Grace is asked by Mythe where she got the painting and upon explaining that she had received it from Miss Pharr and decides to accompany him. Worthy to note, Mythe never tells her that Tiffon is the one who stole the painting from her originaly.
In Ruby's quest, Grace simply joins the team without much story to it.
Grace can be a great tank mage, but although she starts out with all the best water spells (Purify, Bubble Blow and Ice Needles) she has terrible water growth. She is more suited towards Metal elements due to her growth, and in Mythe's story she has the highest LP so should be made a tank/damage soaker. Grace comes with the added benefit of having above-average Skill, making her proficient with Daggers and Bows; though an abyssmal Strength rating prevents her from physically branching out any further.
Regardless of her Water growth being bad, she does start out with the rare and hard to get "Ice Needles" spell and hence a lot of players still use her for that.
Her friendship with Pharr is special, however one can only truly witness it during Mythe's scenario.
Grace is one of only three dark-skinned characters in the game, the others being Mythe and the Silver Girl. The only other dark-skinned character in the whole SaGa series is Harid fromRomancing SaGa 3.
She's one of the strongest female characters in the game. Even though as a female she has less LP, she still has the most LP in Mythe's scenario.