—Elayne Trakand's thoughts of Sereille Bagand
Sereille was raised from the White Ajah and was, quite notably, Mistress of Novices under the previous Amyrlin Seat, Parenia Demalle of the Gray Ajah, before being raised to the Amyrlin Seat herself. She gained a reputation for being tough and a severe disciplinarian, placing strict importance on rules and proprieties. It is possible that Sereille's reputation of austere sternness and disciplinary severity was known of outside her own Ajah.
She used that toughness and discipline and became one of the greatest Amyrlins in history, raising the influence and prestige of the White Tower to levels seldom equaled since before Artur Hawkwing. It was said that Sereille controlled the Tower by the sheer force of her will.
She couldn't stand Cadsuane Melaidhrin because like herself, Cadsuane had an air of control and confidence. They both expected subservience from each other and therefore they would constantly butt heads with each other. Despite this, Cadsuane thwarted a planned coup to overthrow Sereille. The conspirators, thinking that they would gain support from Cadsuane, who was Sereille's biggest adversary, went to Cadsuane to gain her support. This was a mistake. Cadsuane dragged them to the Amyrlin's office herself. Sereille wasn't particularly pleased to obtain help from someone she despised.
She was Parenia Demalle's successor and Aleis Romlin's predecessor. After her passing, there was a large support in the Hall to make Cadsuane Amyrlin rather than Aleis. Cadsuane, wanting to avoid this, avoided the Tower for an entire ten years.