Freya was one of the two Persocoms that were part of a series of Persocoms known as "CHOBITS". She was created because the wife of Ichiro Mihara (the inventor of the Persocoms), Chitose Hibiya, was unable to bear children. All was fine, until poor Freya fell in love with Ichiro. Freya eventually broke from the strain on her circuits. Before she "died", however, she transferred her memories into her younger sister (the other persocom in the "CHOBITS" series), Elda (also known as "Chii"), so that Freya would be able to protect her "sister". Freya is the mysterious Persocom that Chii sees when she closes her eyes. (Source: Absolute Anime)
Freya was the first Chobit, who was created before Elda by Hibiya's husband, Ichiro Mihara. Freya was created to be Hibiya's daughter, because she was unable to bear children of her own. Freya's development was kept secret from Hibiya; she did not know of Freya's existence until she was called down to the lab one day, without explanation. Upon awakening for the very first time, she was given the name Freya by Hibiya.
Freya lived happily with the Mihara couple for a time, until Hibiya noticed that her attitude was becoming increasingly melancholy, with no explanation as to why. At this point, Hibiya asked her husband to build a little sister for Freya, in an attempt to make her happy again. From this request, Elda was created. Freya was happy to have a little sister, and for a time, seemed to be acting normally, although, as Hibiya would later tell Hideki in the anime, "there were still these odd times when she looked as though she was thinking very deeply about something."
Some time after, Freya suddenly lost consciousness and collapsed to the ground. In the anime, the impetus for this event was witnessing her mother and father flirting with each other in the compound's courtyard. It was only then that Hibiya finally realized the source of Freya's sadness; she had fallen in love with her own father, Mihara. Freya knew that her father still loved his wife, and did not want to disturb their happiness, so she pained her heart with efforts to suppress her feelings. Over time, her pain became so great that she began to malfunction under the strain of her emotional burden. Freya was no longer able to move, and was bedridden from that point on. Toward the end, she could not lift a finger or even shift her focus, and began to suffer from memory malfunctions.
In the anime, Freya never found the courage to tell her father how she truly felt; in the manga, she resigns herself to the fact that because of the damage to her body, all hope is lost regardless of the outcome, and chooses to tell him her true feelings. Eventually Freya's pain became so unbearable, that she chose to self-terminate, rather than continue to exist. Before this could happen, Elda offered to take Freya's heart into her own, so that she would not disappear completely, and so that her memories would be preserved. In the anime, nobody knew that Elda had taken in Freya's heart; conversely, in the manga, both Hibiya and Mihara learned of this only moments after it occurred.
Now that Elda has become Chi, Freya does everything she can to ensure that Chi will find the person just for her