She was working in the main house as a maid when Akira, then current leader of the Sohma household, realized that she was 'different' from all the maids, though in reality, Ren was being 'different' so as to get attention from him. They began a special relationship between each other, forming genuine love eventually. When the oldest maid told Akira to stay away from Ren, Akira replied that Ren was the only person who recognized that he was suffering. After a year or so, against the wishes of the maid, they got married.
Afterwards, when Ren (not knowing that she was pregnant) was impregnated with Akito, the future "God" of the Zodiac, the eldest Zodiac members,Shigure,Ayame,Hatori and Kureno swarmed around her. It immediately disgusted her, as small children were crying around her for nothing (when actually, they were crying because of their dream that "God" was being reborn).
When she finally gave birth to Akito, Akira and many of the maids immediately took care of Akito, like she was the head of the household. Ren felt that it was her that should be treated lavishly, since she gave birth to the most important spirit in the Zodiac. As such, it started her hatred of Akito.
Ren is a strong woman who loved her husband with all her heart. However, she is severely mentally ill, mainly because she was jealous of Akito's connection to Akira and felt replaced when she gave birth to her. Although her husband loved her first, she still hated Akito for all the attention Akira gave her. She believed that if she gave birth to a son, her husband would never love another woman. Because she carried a girl instead, she wanted her killed before she delivered.
She has long black hair, much like Isuzu's. She has the same eyes as Akito with both sharing similar face shape and face. According to Tohru, their voices are very alike.
Fruits Basket Manga
Ren told Shigure that Akito and Kureno were in a sexual relationship and that he should get back at her for doing that to him, so Ren has had a sexual relation with Shigure, which resulted in Shigure getting kicked out of the main house by Akito.
She brought a knife with her to try to claim a box that Akito has that is supposed to contain Akira's soul. Akito gave it to her, but when she opened the box, it was empty. One of her eyes rolled to the side while the other stayed in place, bringing even more truth to the claim that she is insane, although she claimed as she walked in that her "head was perfectly clear this morning when [she] thought of this. While Akito always knew it was an empty box (she had already opened it), Ren believe there was something very special belonging to Akira; hence her longing for the box.
It is not known what had happened to Ren at the end of the series, although the old maid told Akito that she heard that Akito had tried to talk with Ren, to no avail.
Ren Sohma appears on the front cover of Volume 21 Fruits Basket.
Akira was Ren's first and only love. When she was younger, she was a maid in the Sohma house; Akira's maid. She would always be his maid, no matter what. But as time moved on, Ren and Akira fell in love, and he married her. Akira loved Ren more than anything. When they had their first child, Akito, Akira seemed to love Akito even more than Ren. This made Ren very jealous of Akito, thereby hating Akito. When Akira died, Ren became depressed and hated Akito even more. She not only hated the fact that her one and only love was dead, but now the one to become head of the family was Akito, the daughter she never wanted or loved.
Ren and Akito truly hate each other, only because Ren was afraid that Akira would love Akito more than her, and jealous when that self-fulfilling prophecy came true. She eventually screamed at Akito when he comes by as Hatori passes her room. She resented having Akito as a daughter, for she thinks that Akira would have continued loving her the most until his death. Because of her paranoia and jealousy, she forced Akito to look and behave like a man throughout her childhood. She mocked Akito and told her that she would be all alone and that no one would ever love her, especially the Zodiac members. This resulted in Akito's own mental illness and her forcing the Zodiac members to stay with her. Akito and Ren's hatred towards each other eventually escalated to physical violence when Akito tried to strangle her mother.
Ren and Shigure, along with Hatori, Ayame, and Kureno, are very close. Shigure once slept with Ren, to get back at Akito for sleeping with Kureno. This made Akito very angry at him, lashing out at him during a meeting between the Sohma and Mitsuru.
- She doesn't appear in the anime.
all information on Sohma Ren came from http://fruitsbasket.wikia.com/wiki/Ren_Sohma