Jin Uzuki. A former solider and a current scholar, he is a mild-mannered and thoughtful man, but not one to be trifled with, as his rival Margulis found on Old Miltia. With both trained under the same school, there'll be no evading a fated confrontation or three between them to settle things. The fact that Jin's unrequited love Pellegri works for Margulis now doesn't really help matters between them.
Like Ziggy, Jin plays the role of responsible adult to the Xenosaga crew, keeping them from flying off the hinge too much. While his sister continually berates him and thinks that her pain is much worse than his, he does try to help her and protect her, even if it's not really his forte.