Madame is a pro-clone advocate who lives outside Hailsham. Alongside Miss Emily, she fights for the rights of clones to be treated humanely before giving their donations. But while Kathy and her friends are at Hailsham, they don't yet know about Madame's political roles. Instead, they know her as the woman who occasionally visits Hailsham and takes away their best artwork for her Gallery.
In many ways, Madame seems like a nice lady. She spends her life fighting for better treatment for clones like Kathy and her friends. She cries when she sees Kathy dancing to "Never Let Me Go" and thinks of all the injustices done to that poor girl. Plus, by the end of the novel we learn that she's even gone into some personal debt trying to keep Hailsham open. Those are pretty generous and caring things to do.
But there's also a darker side to Madame. She is clearly scared of Hailsham students from the start of the novel. And when Kathy and Tommy meet Madame she is very cynical and assumes that they are ungrateful. Plus, she has never given these clones for whom she fights a chance to fight for themselves. So while we give her kudos for not fighting the system, we can't quite give her the standing O she might think she deserves.