Agnes isn't quite the typical heroine in words like Card Captor Sakura. This girl's special power was pretty much sealed by none other than her own father. How? With a rose choker that he put on her, and she hasn't been able to get off since. When it finally does come off though in a freak accident, she gets something much greater than she could have ever imagined. She doesn't really see it that way at first though.
Agnes is awakened as the Rose Princess, who can call forth four nights... by kissing an individual card of the knight's color rose. She can use thorn vines as her power when she gets angry. However, it appears that her abilities to use these only work in reprimanding and controlling her own knights and have no effect on enemies.
Now, why would she have to reprimand her knights, you ask? As it turns out, the four nights under her command are actually boys that go to her high school. Two of them are perfectly happy about having her as their master (the white rose even a little too happy), and the other two at first don't accept her as their master. Kaede, the red rose changes his tune rather quickly when she nearly strangles him with her rose vines, and the other only changes his tune when she attempts to take the fall for something that she and he were both involved in.
At her first meeting with all four, when she's given the power to command, her first thought is world domination. Of course, since the knights use her blood as payment for their magic, her hopes were quickly dashed.
The really interesting thing, though, is that the knights who at first liked her the least are in fact probably the most useful to her. They're also the only two who have been summoned to her individually.
She's not bashful about using her powers for selfish reasons either. She once summoned Kaede almost straight out of the shower, onto her balcony, just so she could talk to someone. Her language is also not fitting of a princess. She isn't reserved in the way she says things. What she says is usually blunt and to the point.
Unlike many series where the girls' reactions are overboard, Agnes pretty much reacts the way that a normal girl would in some situations. Like when she tried to feed her moody black rose knight, Mutsuki, a sandwich, and he proceeded to eat it from her hand, followed him rubbing his face like a cat against her arm. Rather than getting turned on and falling for him like many manga girls would, Anges tethered him with her vines, and proceeded to tell him to take the sandwich and eat it by himself, before she disappeared.
On the other hand, she's not all hard as nails either. Her knights have made her weak at the knees on more than one occasion, and when they get injured it bothers her.
As a character, she's quite strong, but she's also completely naive. She wants it all and claims that she's willing to pay the price, but she doesn't stop to ask what the price is. She's not completely stupid, because her common sense is in fact quite good. She's prone to peace, but isn't afraid to use force if necessary. On the flip side, her tendencies to use her influences for selfish reasons may get her in a world of trouble before long. Though the latest development in this regard has yet to be seen.