Brother and Sister (XS2)

 is a track in Xenosaga Episode II. It has not been released on any soundtrack or sound selection and not much is known about this track. It plays in the following cutscenes:
 * Jin apologises for subjecting chaos and Jr. to his and Shion's argument at dinner.
 * Jin and chaos discuss the events of 14 years prior and Jin's relationship with Shion at night outside the Uzuki Residence.