Ichigo's mother was a princess from the royal family, and Isshin was captain of the imperial guards, while Aizen was a genius and talented newbie shinigami.

Aizen, Isshin, Mother = Good friends

Isshin and Aizen loves mother, but due to Aizen was still newbie, mother's father(head of the royal family) restrict Aizen to meet with mother, looked down on Aizen, cuz Aizen back then was still nobody.

Both mother and Isshin in love, and mother pregnant.

Aizen felt sad and hates the head of the royal family. Started planning his PERFECT PLAN to revenge againts the royal family. Farm everyday, until he super pro.

Aizen created a trap, made Isshin heavily injured, almost die.

Aizen tells mother only way to saves Isshin is to use hollow magic.

Mother trust Aizen, practices hollow magic, and really saved Isshin.

Head of royal family found out his daughter practice hollow magic, sentenced daughter and Isshin death.

Mother and Isshin cabut to real world, both sealed away their super powers, so SS cannot detect them.

Mother before sealing away her super power, knew Aizen would come for her child(Ichigo), so mother uses the hollow magic, and placed a super protector into Ichigo, which is the hollow inside ichigo, to protect ichigo.

Mother kena pawned by Grand Fisher cuz that time mother's power was sealed away long time ago, so no power fight, so mati.

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Added on March 27, 2010, 1:40 am"Aizen : In addition you were special from the moment of your birth. Because you are a shingami and..you are the heir of the royal family, heir to the throne"

This explains why the hollow inside Ichigo once addressed Ichigo as "King"

Also explains that Aizen cannot be Ichigo's father, as he looks so young, while Isshin looks much older thus most likely is the father.

ahhh clever mirian high five *piaks.. ya even his dad cant feel the reiatsu but ichi can do it