At the beginning of the game, Wild Arms 2, Merill is a girl in her early teens living in the town of T'Bok. She happens upon the hiding prisoner of war, Brad Evans and attempts to save him from purusing soldiers. When her life is threatened by those soldiers, however, Brad gives himself up to spare her.
Staying at the village, she spends the intervening time before the game's main story taking care of the lost dog Rassyu and Brad's war-buddy Billy Pilder. Brad is shocked by the beautiful woman she's become and even seems to declare some romantic intent to her (though the game's translation makes this impossible to tell with clarity).
While she gives up Rassyu to Brad, she continues to take care of Billy until the end of the game's story, where it appears he's recovered from his injuries. Though Brad apparently returns to T'Bok, there's no mention made of Merrill in the closing sequence.