This guide will be more complete than Sega's or other guides, and was updated with new information as it was released on the characters as new online chapters were released. This means it will have both offline and online story components mixed in, as the characters are all re-occurring.
RED TEXT- Assumptions, questions

These are the NPCs you play as (Ethan) or team up with frequently throughout the game, online and off.

Ethan is the main character who you play throughout the story. He is a regular kid living with his little sister on the Guardians Colony. He likes to play and is good at ###. His rival at this is Hyuga Right. His father Olson Waber was a guardian, but died in the service. Because of this, Ethan starts out disliking Guardians and their authority. He blames the organization for his father's death. Shortly after his father died, his mother had Lumia, and died as well.

When SEED attacks the colony, Ethan proves he can be a bit of a hero, by helping ordinary citizens escape the danger, and rescue his sister. Leo Berafort convinces him to join the Guardians. Ethan moves into a Guardians quarters after joining the organization. He continues his Guardians training, and then missions with Leo, Hygua, Karen, Tonnio and Maya.

Later on, in other games you discover that his father Olson Waber was a prisoner of an evil organization for most (?) of Ethan's life, and also not actually dead. You end up rescuing his father and putting the family back together again later on.

Karen joined the guardians when she was 14. When Karen was very small, her mother took her away from her original family. While they were running through the forrests of Neudiaz, wild animals ate her mother. Everyone thought they had both died. Instead, an ordinary family of newmans, the Shidows, found her and adopted her. Maya Shidow is her adoptive sister. Where does the last name "Erra" come from? Neither family has it.

Karen cannot use techs, which is strange because of her newman heritage. She thinks it is due to the trauma she experienced when her mother died. Karen pushes herself very hard to achieve everything she sets out to do. She is strict with herself and others equally, and comes across as somewhat of a pushy or overbearing. She seems to have feelings for Ethan as the story goes on, but she is not open in the least.

Karen cannot cast techs because of the Photon Seal on her hand. These seals were used a long time ago to etch recovery technics into newman who were high ranking. Presumably, they'd "go off" if the person was attacked or injured, and protect them. The seal appears as a glowing circle with symbols inside. These Photon Seals were banned long ago because people discovered they could hide deadly or harmful technics inside themselves or others. Presumably, if a technic is in a seal it could be smuggled in undetected unlike a weapon, or used without the person's knowledge.

Dohgi Mikuna, Karen's father wanted to be sure that the Mikuna legacy continued producing a line of Holy Maidens. Apparently, very spiritual women run in the family. For some reason, Mrs. Mikuna had twins and one of them was not very healthy. Mirei was the less-healthy and more spiritual twin. Dohgi placed Photon Seals on both girls hands. Karens' seal drained her TP/MST and channeled it into Mirei. This caused Karen to not be able to use techs, as her energy was drained too quickly by the Seal. When her mother ran away with Karen, it was to escape Doghi's plan. He needed to sacrifice Karen in order to complete Mirei, and ensure that she had a naturally long life, and complete Divine Maiden Powers. (He plotted to kill one sister to fix the other)

After Mirei's death, Karen disguises herself as Mirie/Divine Maiden, to carry on her sister's good works for the COG.

Name: Maya Shidow
AKA:
Relations: Karen Erra-Adoptive Sister
Age: 24
Association: Guardians
Special:
Look: Newman, pale tan, long hair

Maya is Karen's adoptive sister. She is seen as beautiful and outgoing. She dresses in a very provacative manner (think deliberate boob-window clothing, etc) and uses her body to get what she wants. She flirts and uses her sex-appeal to get away with things that others couldn't. She is not actually a slutty person, and does not behave badly or act mean. Her personality is silly and friendly, and she likes to joke and tease with her friends.

She studied under the A-Photon researcher Kou Toragi, and is actually quite smart. She is interested in photon research, and Synthing. It seems that she liked Kou, and possibly dated him, although she did not agree with him. She still cares about him, but is mad. When Kou finally confesses that he loves her, she says she returns his love, although it is too late. She vows to continue his research. She invents different kinds of synth boards for food, but isn't very good at it and the food often turns out terribly. She also cannot cook well at all.

Name: Hyuga Right
AKA:
Relations:
Age: 17
Association: Guardians
Special:
Look: Human, light-tan, white short wavy hair

Hyuga is Ethan's rival at the Guardians, and in ##. He is a smooth and sophisticated character who does not get easily excited or angry. He is a strong believer in the COG. Hyuga is also a self-proclaimed 'ladies' man' and is always looking for a date. He uses religion to initiate conversations with women and help him appear more sophisticated. (Since the solar system seems fairly mono-religious, it's probably an ok tactic) It is revealed that he will hit on nearly anything female that moves, as he tries to pick up Ethans' sister, by asking her to an amusement park, despite knowing that she is 13, and he is 17! Some observers may find that somewhat creepy. He is structured to be decent looking, and his personality is not set up to be obnoxious/grating/something wrong with it so why don't any of the girls stay?

Name: Leogini Santosa Berafort
AKA:
Relations: Wife- , Son-
Age: 31
Association: Guardians
Special:
Look: Beast, tan/tan short hair, small hairy ears

Leo is the oldest member of the group. He seems like a gruff character, but once you get to know him, he is caring and loyal. He is very level-headed, and usually has a plan, or can step in to break up arguments. He is experienced at being a guardian, and makes good decisions. He has a 3 year old son and a wife back on Moatoob. However, he seems to also care about Laia Martinez, who clearly has a crush on him. Leo helped convince Ethan to join the Guardians.

Name: Tonnio Rhima
AKA:
Relations: Liina Sukaya-Adoptive Sister
Age: 26
Association: Guardians
Special:
Look: Small-Beast, short tan hair

Tonnio was in an orphanage on Moatoob growing up. He and Liina Sukaya consider eachother like family from their days in the orphanage. After his stay at the orphanage, he became a street thug, then a gang leader. He was friends with/somewhat raised by the Evil Miner Woman##, who he then deserted when he took up being a guardian. His personality is very childish and he is hot headed and offensive, even toward people he trusts. He jumps to conclusions, and persecutes others for their looks--or anything else he can think of. He seems to enjoy getting into fights and arguements. He is very aggressive.

Tonnio may have feelings for Liina, but she is in love with Alfort Taylor instead. In the end, he proposes to Liina, but she is still thinking about it.