Kirsten Cohen (maiden name Nichol) is a fictional character on the FOX television series The O.C., portrayed by Kelly Rowan.

Originally portrayed as being unwelcoming towards Ryan in the Cohen household, she began to develop feelings for the brooding teenager, going on to accept him as a central member of her family.

She comes from a very wealthy background: her father is a real estate developer who founded The Newport Group, one of the most powerful companies in California.

Although the Nichols appear to be the envy of Newport, Kirsten has stated multiple times that she was unhappy with her family life due to her distant and domineering father, alcoholic mother, and rebellious sister.

In contrast to her husband, who campaigned for Democratic presidential candidate Walter Mondale in 1984, Kirsten was relatively conservative and supported the Republican Party because her parents did.

She is generous, sympathetic, and fiercely protective of her family, including Ryan, to the point where she extended her kindness to his biological mother Dawn and ex-girlfriend Theresa.

[6] However, her absence was keenly felt when she was in rehab for her alcohol problem at the beginning of season 3 as the household descends into disarray, evidenced by the messy kitchen and empty refrigerator.

The rest of the season focuses on the Cohens adjusting to the newest member of the family, with Kirsten becoming a mother figure in Ryan's eyes.

Although Kirsten has a mostly stable marriage compared to the other main characters, her close friendship with next-door neighbor and ex-boyfriend Jimmy Cooper causes tension and awkwardness between her and her husband.

In the first-season finale, Kirsten hints to Theresa Diaz, Ryan's pregnant ex-girlfriend, that she had an abortion early in her life.

The problems begin for Kirsten during the second season when she fears that her husband is cheating on her with an old girlfriend, Rebecca Bloom, who has mysteriously shown up back in town.

Her alcoholism is fueled by working closely with a man whom she has a crush on, Newport Living magazine editor Carter Buckley, who also drinks too much.

She was initially resistant and defensive but agrees after seeing a distraught Seth and hearing the usually reticent Ryan talk about how his alcoholic biological mother refused to seek help.

Seeing the letter as a threat to the progress she made in rehab, she runs away and spends the night in a motel with a bottle of vodka, "but I didn't drink," she tells Sandy later.

Kirsten returns home and creates a high-class dating service, NewMatch, with long-time friend and one-time stepmother Julie Cooper-Nichol.

Seth, fearing that Ryan was on the warpath, intentionally gives him the wrong address, and his parents show up to bring the boys home.

A family crisis appears again when Frank, an accountant Bullit brings in to deal with NewMatch's books, reveals that he is Ryan's biological father.

After hearing their parents reminiscing, Seth and Ryan fly to Berkeley to find their old house, but the current owners are unwilling to sell.