Madeline's son, Sean, was very loyal to his mother. Sean killed an Oversight member, who exposed Madeline's identity to Nikita in "Clawback". Then he destroyed the Black Box for protecting her in "Fair Trade".
In "Clawback" Madeline offers Sean to replace Amanda as a head of Division citing that Division needs "someone straight and true". Sean agrees to consider the offer, if Madeline convinces other members of Oversight to spare Ryan Fletcher life. Madeline later tells Sean, that she failed and that Fletcher is dead. When Madeline questions Sean about killing Gaines, he answers he did it for the same reason he is going to capture Nikita and stay with Division for the time being - to protect Madeline.
Madeline is shown not to take Nikita threat too seriously at the beginning. In "London Calling" Sean points out to her she has to "take this seriously". Madeline answers, that she already has her own security and that Nikita would never risk a direct attack on United States senator.
In "Fair Trade" Madeline calls an emergency Oversight meeting, after Nikita uses the Black Box to steal 80 million dollars from Oversight account. Nikita has Birkhoff put tracker into Madeline's coffee, which she uses to locate Oversight meeting place. When meeting is disbanded pretty much before it starter Madeline is the one to spot Nikita, sending Sean in futile pursuit.
Madeline later conferences with Amanda over the phone, agreeing to exchange Birkhoff for the Black Box, stating that the Box is their priority. In Sanctuary Oversight members meet to discuss their future actions. While Bruce proposes to dispose of Division by activating a Clean Sweep protocol, which will release a poisonous gas into Division, Madeline opposes such a plan. She gets Sean to agree to oversee the dismantling of Division, before he leaves the meeting site. However Madeline is still outnumbered three-to-one, with other Oversight members in favour of implementing Clean Sweep protocol.
In "Sanctuary" Madeline and her colleagues got captured as hostages by Guardians. They threaten to kill all the members of Oversight and to execute Clean Sweep if Percy isn't released. Madeline hides her cellphone into the pocket, so Sean and Nikita's team could hear.
In "Clean Sweep" Sean joins Nikita and Michael to save save his mother. Patrick Miller killed all of the members except Madeline. Sean found her in the house surrounded with dead bodies of the members of the Oversight. After finding out Oversight is destroyed, Amanda tells Madeline she is no longer under her control. Madeline offers Nikita and Michael to clear their names with the Presidential pardon if they agree to take down Division. Though Sean reminds his mother that she will likely be imprisoned for exposing Division to the President, Madeline stated that she will gain immunity for her silence.
Though she doesn't appear on screen, in "Power" Madeline supplies Michael with information about Division's involvement in a prototype helium-3 generator robbery attempt.
- Madeline Pierce was the only female member of Oversight group.
- According to the information on her site shown on screen Madeline grew up in New York and had shown interest in politics already since school.
- Madeline has bachelor's degree in history and political science from Yale University and a law degree from Harvard University.
- Madeline has three children. Her daughters Jill and Sandy are both lawyers. Sean is the youngest child and is a Navy Seal.
- As a senator Madeline Pierce serves her fifth term in office.
- The same actress that plays Madeline in Nikita also played a character by that name in the TV series La Femme Nikita, albeit in that production Madeline role was the same as Amanda.