Cosette d'Artagnan

Cosette Marie de Batz Castelmore D'Artagnan (also known as Cosette d'Artagnan and Charles d'Artagnan in public) is the protagonist and one of the four titular characters in D'Artagnan and her Musketeers and its sequel by Quill Sparkle.

Biography
View Cosette's biography here

Physical appearance
Cosette is a young woman who is fifteen-years-old (turning that age a  couple of months prior to the book beginning, later 16). She wears a make-shift corset her father made for her so she won't be recognized as a girl. She also has mid-length short hair to not give away her gender.

In the recent years, Cosette's hair grew out longer, possibly reflecting on her feminity being revealed to her friends in the series. According to Aramis and Porthos, Cosette is sixteen years old, with short dark hair and brown eyes.

Possessions

 * Sword
 * Sapphire - her pet horse that was a gift from her mother 

Athos
out of all the Musketeers, Cosette and Athos are the closest siblings in their company. Like the original, Cosette thought Athos killed her father and rendered her an orphan and attacked him without hesitation. However, after saving his life, Athos appears to have warmed up to Cosette by the end fo the episode, joining her card game with Porthos to prevent Porthos from conning who he calls "[their] new recruit." During the third episode, Cosette's and Athos' relationship has improved, as they now consider each other friends. However, Cosette finds it irritating that Athos doesn't open up to her like he does with Aramis and Porthos. However, he finally decides to finally open up to Cosette what happened to his wife, something he never shared even with Aramis and Porthos. She promises to him that she won't tell them what happened between them.

In chapter 33, he finally learns her secret but lashes angrily out at her. Later, Athos is revealed to have tried to get Cosette out of being a Musketeer, he failed. But he did this only to protect her. He mentioned to Henry that Cosette would no longer be a Musketeer if she gets herself or anyone else hurt on her account.

Aramis
Cosette and Aramis didn't have a healthy relationship with each other at first, as they dueled against each other since Cosette nearly killed Athos. He often has to hold Cosette back when she goes too far, such as putting a hand on her shoulder to both stop attacking the guard they were trying to interrogate and comfort her at the same time. He often gives Cosette tips about relationships.

Aramis learns she is a girl in episode ten when going to patch her up after being wounded by Athos, but immediately forgave her. From that point on, Aramis continues to call her "sister" or "little sister."

For more it Cosette and Aramis' relationship, see here.

Porthos
Despite not interacting much with Porthos, he and Cosette have a close companionship. Cosette had the upmost sympathy for Porthos when he talked of slavery and revealed personal things about his mother. She excessively worried about him during "The Homecoming," especially instead of saying she was as worried as that, instead Cosette said that to Aramis in order to probably control her worry.

Constance Bonacieux
Constance is an older sisterly figure towards Cosette. At first, the two of them do not get along and Constance think it is foolish that Cosette is pretending to be a boy to kill Athos. However, they begin a friendship after the ordeal is over. Cosette even allows Constance to call her "Cos," a nickname all her friends use. Constance even keeps her secret from Athos, Aramis and Porthos and helps Cosette sometimes embrace her feminine side. During Chapter 5: Gaining Trust, Constance was lied about Cosette's arrest by the other Musketeers and was infuriated with them for not helping her when they were supposed to avoid the duel in the first place. When told the truth, part of Constance is annoyed but relieved when Cosette rturns home safea nd sound.

However, their relationship is strained when Bonacieux, Constance's husband threatens to reveal Cosette's secret to the Cardinal if she doesn't break her friendship off with Cosette. Of course, Cosette is unaware of this and is actually heart-broken when Constance breaks the friendship with her.

Milady de Winter
Cosette first encountered Milady when staying at an inn at Paris. However, she came in on a terrible time, since Milady framed Cosette for murder. Milady  first introduced herself as "Anne," and said that as women, they should stick together. Cosette didn't know her as Milady de Winter yet, shown when she denied knowing anyone named "De Winter."

According to Cosette, Milady is very beautiful and says that they have unfinished business.

In season 2, Cosette developed a friendship with Milady even Milady apologizing for revealing Cosette's secret.

Her sisters
Cosette loves her sisters dearly and cannot bring herself to tell them of their father's deaths until she has avenged him. Though they disapprove of her masquarade as a boy, they nonetheless support her.

Jacques and Adam Beauchamp
Jacques and Adam Beauchamp are a pair of brothers, Isabelle and Amelia's husbands and  Cosette's brothers-in-law. The two men treat Cosette as the little sister they never had since they only have a younger sister. They defended her against Porthos when they thought he was beating her. They know of her secret and worry about Cosette but learn she can fight quite well when fighting off bandits.

Sapphire
Sapphire is Cosette's pet horse and, after the farm is burnt down, the only connection she has to her mother. She was a gift to Cosette from her mother, Renée, and uses her when travelling to find Athos' innocence. The two fo them trust each other completely, and Sapphire loves it when Cosette feeds her carrots.

She also is the fastest horse in France, even cornering Emile Bonnaire when he attempted to escape, showing a good faith Cosette has in her horse.

Abilities
Mistress of Disguise: Cosette is an extreme talented mistress of Disguise, as she was able to convince her friends into thinking she was a male. However, Cosette is not proud of it.

Family

 * Françoise de Monesquoiou d'Artagnan  † - Mother
 * Alexandre d'Artagnan † - Father
 * Amelie d'Artagnan - Sister
 * Niece
 * Jaques Dubois - Brother-in-law
 * Adam Dubois - Brother-in-law
 * Charles de Monesquoiou † - Maternal Grandfather
 * Josette de Monesquoiou † - Maternal Grandmother
 * Paternal Uncle †
 * Espoir - Cousin
 * Musketeers - Teammates and Friends
 * Inseparables - Temporary Enemies turned Recruiters, Friends and Partners
 * Athos - Adopted Brother, Mentor and Patron
 * Porthos - Adopted Brother
 * Aramis - Adopted Brother

Allies

 * Musketeers - Teammates and Friends
 * Treville - Father Figure, Captain and Godfather
 * One-Eyed Florian
 * Jacques the Stable Boy
 * Antoine †
 * Edward
 * Dubois
 * Constance Bonacieux - Best Friend
 * Paulette Planchett- Childhood Friend
 * Royal Family of France
 * Queen Anne - Queen
 * King Louis - King
 * Prince Louis
 * Christine, Duchess of Savoy
 * Paul Meunir - Enemy turned Ally
 * Leon - Pursuer and Former Enemy
 * Drunk Woman
 * Morgue
 * Poupart
 * Pastor Ferrand - Situational Ally
 * Court of Miracles
 * Flea - Friend
 * Agnes Bernard
 * Henry Bernard
 * Ninon de Larocque - Friend
 * Fleur Baudin - Friend
 * Convent
 * Sister Teresa
 * Mother Superior
 * De Foix family
 * Lucy de Foix
 * General de Foix
 * Simone Peppin
 * Monseur Pepin †
 * Doctor Lemay † - Friend
 * Emilie
 * Catherine
 * People of Pinon
 * Jeanne - Friend
 * Bertrand
 * Robert † - Savior
 * Camille
 * Vargas

Enemies

 * Armand Richelieu † - Former Captor
 * Jacques-Michel Bonnaire †
 * Milady de Winter - Situational Ally
 * Comte de Rouchefort - Situational Enemy turned Attempted Killer and Victim
 * Red Guards
 * Captain Gaudet † - Attempted Killer and Victim
 * Dujon † - Assault Victim
 * Gaudet † - Victim
 * Vadim's Men
 * Vadim † - Attempted Killer and Victim
 * Felix †
 * Bonnaire family
 * Emile Bonnaire
 * Maria Bonnaire † - Temporary Captor
 * Thibault
 * Meunir's Men – Attackers and Temporary enemies
 * Marsac † - Attempted Attacker
 * Cluzet
 * Victor Amadeus
 * Emile de Mauvoisin †
 * Valet de Mauvoisin † - Attempted Killer
 * Vincent
 * Marie de Medici
 * Luca Sistini †
 * Charles Gallagher † - Attempted Killer
 * Sarazin † - Victim
 * Marguerite † - Ally turned Enemy
 * Gus †
 * Spanish - Temporary Captors
 * Edmond
 * Renard
 * Marmion
 * Levesque family
 * Monsieur Levesque
 * Eleanor Levesque - Attempted Killer
 * Sofia Martinez † - Former Ally
 * Francesco †

Foils

 * Cosette serves as a foil to milady de Winter.
 * Both are beautiful young women who use aliases rather than their real names. (Cosette uses her last name but uses Charles as a first name and Milady's name is really Anne de la Fère).
 * They wear disguises and often manipulated others around them, mainly having anything to do with their appearance with Milady uses her looks in seducing men while Cosette uses her disguise as a man to make people think she is a boy.
 * They both hide their past from their friends and family (Cosette only discussed her father but not her sisters to her friends while Milady.
 * They have pretended to be something that they are not. (Cosette a boy and Milady a woman of noble background). However, while Milady takes joy in her lies and deception, Cosette feels extremely guilty for keeping it secret.
 * They also deceived Athos based on pretending who they are when they first meet him. In Milady's case, she pretended that she was of noble background . Meanwhile for Cosette, she pretended to be a man. Their identities are revealed very similarly but differently: milady by her killing Thomas but in self defense and for Cosette, being coerced by Milady to tell Athos who she is.
 * When they are truly revealed, Athos reacts differently between their betrayals. Athos finds Anne guilty of murder for killing his brother and nearly had her killed. However, Milady was never killed. With Cosette, Athos gives her the silent treatment until Cosette comes up to him to ask for forgiveness.
 * She is also foil from Constance, Cosette is young, has dark hair and dark eyes and is not married. Meanwhile, Constance is married and has red hair and blue eyes and pale skin compared to Cosette’s tan skin tone. Also, Constance is more feminine and hardly wields weapons and Cosette is more of a tomboy and does use swords.
 * She is also different from Athos:
 * He's usually calm and level-headed while Cosette sometimes things rash.
 * Most definitely it's their age difference. Cos is a teenager but Athos is an adult, in his thirties. They both have dark hair but Cosette has brown eyes while Athos has blue. Also while Athos appears cautious trusting people, Cosette tried helping others.
 * Cosette and Athos are both fairly talented and in the same sword fighting level.
 * Also, while Athos takes the older sibling role, Cosette has the younger sibling role.
 * While Athos has a younger brother, Cosette has two sisters.
 * Also, Athos is of noble birth while Cosette comes from Farmers.