As the leader of your group, the main character takes two important people under his wing. The important one for this event is a boy who living things into stone by looking at them. He lives in a giant mansion with his butler, and is terribly alone. He also can't remember his past before he lived in the mansion, which just makes things worse. You and the other member of your group end up helping the boy figure out his past, but that also makes things worse. Turns out, he and his sister were donated to a military research clinic a few thousand years ago. The only reason he's still alive is because he and his sister were candidates for becoming living weapons and thus were kept in stasis as long as possible. After discovering this, his sister awakens from her stasis, only to have completely lost her mind. So you kill his sister and he takes on her form in order to become even better at killing things with you and the group.
That's his backstory, and it's rather depressing I believe. What's nice, though, is that the more you progress through the story, the more attached the group becomes. So even through the death of his sister, the past abandonment of his parents, and his transformation into the living weapon (think Jack Skellington, but short), he's managed to retain a slightly positive outlook on life because of his friends. Then there's the boss fight.
The boss fight is against a pair of twins (immune to aging) and you end up killing the first and hurting the second. In order to get revenge, the second twin attempts a "You're all coming with me" move. Living-weapon-boy comes to the rescue by shielding everyone in the party and moving them out of range of the blast radius. Unfortunately, he can't get them through fast enough, so he pushes himself out of the anti-magic field, propels you and the group to safety, and dies from the final attack.
I had grown rather attached to this character, like insanely attached, and he had just died because of the actions taken by the final boss and his minions. Some people were watching me play this part, and one of them spoke up after the cutscene with a "well that sucks." I almost went berserk because I was saving the rage I felt for the entire room full of low-level, low-hitpoint cannon fodder which was graciously provided for me immediately after the cutscene. Now that I look at the scene again, I'm not quite sure why I was so angry, instead of saddened (like I was with Aeris), but ah well. The game ranks in my top 5 because of the emotions it made me feel the first time through. I've never had a game produce emotions other than sadness and joy (depending on how involved I am in the story), and so this one surprised me.