Be any character you want via the anime/manga or feel free to create your own. I'll use mine as an example.
Yue_Shadow
Name: Shadow Rockwill
Age: 21
Alchemist: Yes
Allegiance (Miltary, Elrics, etc.): little bit of everyone's...he has a connection to all of them
Bio: Shadow's physical body is fairly new but his soul has been around for over 400 years. He originally aided Dante and Hohenheim in the creation of the first philosopher's stone but was caught up in Dante attaching Hohenheim's soul to other men. His own soul was forced out of his body and was at rest in the gate until the soul of a newborn infant became merged with his own. He then was reborn as Shadow Rockwill, half Ishbalin from his mother's side. During the Ishbalin massacre, his mother was caught up in the terror and executed. With 6 older brothers and 12 younger sisters, all half siblings and none Ishbalin, Shadow was isolated until he 'joined' the military for his unmeasured theories and alchemic skills. While in hiding, he meets Ed and Al and agreed to teach them so long as they don't draw the military attention to the point he might be discovered. Just like Ed...he has a great deal of automail, though very unconventional.
Appearance:
Age: 21
Alchemist: Yes
Allegiance (Miltary, Elrics, etc.): little bit of everyone's...he has a connection to all of them
Bio: Shadow's physical body is fairly new but his soul has been around for over 400 years. He originally aided Dante and Hohenheim in the creation of the first philosopher's stone but was caught up in Dante attaching Hohenheim's soul to other men. His own soul was forced out of his body and was at rest in the gate until the soul of a newborn infant became merged with his own. He then was reborn as Shadow Rockwill, half Ishbalin from his mother's side. During the Ishbalin massacre, his mother was caught up in the terror and executed. With 6 older brothers and 12 younger sisters, all half siblings and none Ishbalin, Shadow was isolated until he 'joined' the military for his unmeasured theories and alchemic skills. While in hiding, he meets Ed and Al and agreed to teach them so long as they don't draw the military attention to the point he might be discovered. Just like Ed...he has a great deal of automail, though very unconventional.
Appearance:

