Guizin is the long suffering wife of the philandering Turkish Cypriot, Mehmet Osman. She first arrives in Albert Square in October 1985 when she comes to inform her sister-in-law, Sue Osman, that her husband, Ali Osman, had gambled away the mortgage money for the home they were planning to buy.
Guizin and her three children, Emine Osman, Rayif and Murat, later move in with her brother-in-law and his family in 1987, after her husband gambles away their home and deserts them. She works for Ali and Sue in the café for a few months until her husband returns and she becomes a partner in the business. As part owner of the café, she hires Ian Beale, who later becomes the sole owner.
Guizin and Mehmet's marriage is highly turbulent and they are always involved in intense arguments, mainly concerning money and gambling. Guizin is well aware of Mehmet's flaws and adultery, but unlike Sue, she is willing to turn a blind eye to most of her husband's dealings to keep the marriage together because, in her community, that's what a wife is expected to do. Guizin may put up with a lot from Mehmet, but she is certainly no pushover, and is more than willing to defend herself and her family if anyone should cross her. She has numerous rows with Sue over the years and she nearly comes to blows with Donna Ludlow after she informs her that Mehmet had been trying to seduce her on New Year's Eve 1987. Yet more animosity arises when she discovers that Mehmet has been sleeping with prostitute Mary Smith, but although Guizin gets extremely angry, she ends up forgiving Mehmet for the sake of the family. However, there is one affair that Guizin is not willing to forgive Mehmet for, and it happens to be the only one that he did not actually have. After Sue discovers that Ali had slept with Donna Ludlow, she kisses Mehmet in front of Ali for revenge, causing a huge fight between the brothers. Ali tells Guizin about Sue and Mehmet's suspected affair, making Guizin furious. She viciously attacks Mehmet in the middle of the Square and leaves for Northern Cyprus, taking her children with her. Her last appearance is in March 1989. Mehmet leaves England soon after to attempt to patch up their relationship.