The character first appears in Harry Potter and the Order of the Phoenix (2003) as part of the advance guard sent to the Dursleys' to bring Harry to Grimmauld Place. She is described as having "...a pale heart-shaped face, dark twinkling eyes, and short spiky hair that was a violent shade of violet." She despises her given name and prefers to be called by her surname alone. Tonks explains to Harry that she is an Auror and a member of the Order of the Phoenix. She says that she is a Metamorphmagus. As Tonks explains: "Metamorphmagi are really rare, they're born, not made." She is a shape-shifter who can change her appearance at will (she seems, however, limited to a human-like form, although she has also been seen to transform her nose into those of different animals) which she can use not only to disguise herself in the line of duty, but also for experimenting with her appearance, and even for her friends' entertainment. Rowling also adds a comical side to Tonks's character: she is notoriously clumsy and unskilled at household spells, like cooking, cleaning, and setting the table, and frequently breaks things and trips.
Tonks is, by heritage, a half-blood: the daughter of pure-blood witch, Andromeda Tonks (née Black), and her Muggle-born father, Ted Tonks. Her mother is sister to Bellatrix Lestrange and Narcissa Malfoy, and bears a resemblance to Bellatrix; upon her marriage to a Muggle-born, her family disowned her.
Tonks is an only child, raised in the wizarding community in a house near the Weasley's. She studied at Hogwarts and was sorted into Hufflepuff. She was born in 1973 and entered Hogwarts in 1984, the same year as Charlie Weasley.
The character later mentions that she left Hogwarts in 1991 and began three years of Auror training. As a Metamorphmagus, she barely had to study for her Concealment and Disguise exam but had difficulty with Stealth and Tracking due to her clumsiness. Nevertheless, she qualifies as an Auror in 1994, one year before her first appearance in the Order of the Phoenix.
Andromeda was responsible for naming their child Nymphadora, a name Tonks utterly detests. In the last and final book, she marries Remus Lupin and gives birth to a son, named Teddy Remus Lupin, after her late father and her husband.
The Black Family greatly valued blood purity and therefore disowned Andromeda for marrying Ted. For this reason, Andromeda is considered a blood traitor by the old wizarding families and Tonks isn't considered a member of the Black family. She isn't on the Black family tree and Sirius noted that Kreacher, who is supposed to follow the orders of all family members, refuses to obey her. It is likely that her aunt Bellatrix deliberately hunted her down and killed her during the second Battle of Hogwarts due to this 'blood traitor' status being a perceived stain on family honour, not to mention her marriage to the werewolf, Remus Lupin.
In Order of the Phoenix, Tonks describes her mother Andromeda as having a talent for cleanliness, but Ted was "a right old slob". In Deathly Hallows Andromeda is described as being strikingly similar in appearance to Bellatrix Lestrange, her sister. Tonks's parents don't share Bellatrix's allegiance to Voldemort, providing a temporary safe haven for Harry early in the book. Later in Deathly Hallows, Tonks's Muggle-born father was forced to flee his home when he refused to submit himself to the Muggleborn registration decree, on the principle of the thing, as Voldemort stepped up the persecution of those not from "pure" wizarding families; he was later apprehended and murdered.
In Order of the Phoenix, Sirius described Andromeda as his favourite cousin, but Tonks had little opportunity to get to know her relative, due to his longtime imprisonment in Azkaban and death a year after they became acquainted. Narcissa Malfoy and Bellatrix Lestrange, Andromeda's sisters, are Tonks's aunts and Lucius Malfoy and Rodolphus Lestrange are her uncles by marriage. Draco Malfoy is her first cousin, though neither she nor Draco acknowledge this; in Half-Blood Prince Tonks dispassionately refers to Draco as "the Malfoy boy".
Tonks is introduced early as a member of the Order in the book Harry Potter and the Order of the Phoenix. At the time, she, and senior Auror Kingsley Shacklebolt, were acting as spies for the Order at the Ministry, which strongly opposed Albus Dumbledore and Harry Potter. Officially they were assigned the Ministry task of tracking down and monitoring Death Eaters activities and hunting Sirius Black, a fugitive and refugee hiding in his own house: the hidden Headquarters of the Order at Number Twelve, Grimmauld Place. Indiscreet action at the Ministry would have cost Tonks and Shacklebolt their positions, due to the prevailing anti-Dumbledore policy. However, they were able to supply intelligence to the Order about the Ministry's activities.
Tonks helps to escort Harry first from the Dursley family house to Order headquarters, and later to the Hogwarts Express train at King's Cross railway station for school.
Tonks later fights the Death Eaters at the Department of Mysteries, together with Alastor Moody, Sirius Black, Remus Lupin, Kingsley Shacklebolt and Albus Dumbledore. She was injured by her aunt, Bellatrix Lestrange, and had to be taken to St Mungo's hospital. She was fully healed and released, and a short time later got together with Alastor Moody, Remus Lupin, and Arthur and Molly Weasley to confront Vernon Dursley about Harry's treatment at Number Four Privet Drive.
During Harry Potter and the Half-Blood Prince, Tonks is stationed at Hogsmeade and assigned to guard Hogwarts. Harry observes her behaving uncharacteristically: she is constantly depressed, rarely smiling or acting friendly. Her hair, normally a vibrant pink, was always a mousy brown colour, her abilities as a Metamorphmagus were also disturbed, and her Patronus changed some time after the battle from its original form to a large, silvery, four-legged animal. Such changes were held to be evidence of extreme shock or strong emotions. Harry and his friends assume that her evident depression is due to Sirius Black's death. Harry speculates that Tonks might have been in love with Sirius (despite Tonks and Sirius having been related), since he thought that her Patronus resembled Sirius's Animagus form. The Weasley children, (particularly Ginny), speculate that their mother is trying to match Tonks up with their brother Bill, because Molly Weasley keeps inviting Tonks for dinner. After Albus Dumbledore's death, it is revealed that Tonks had fallen in love with Remus Lupin, and her patronus had as a result changed to the form of a wolf. When he was reluctant to return her affections (believing he was too old and it was too dangerous for her to be involved with a werewolf), her depression muted her magical abilities. Tonks appears to have been consulting Molly for comfort and advice. At Dumbledore's funeral, it appears that Tonks and Lupin were now a couple; they are seen holding hands and Tonks's hair has returned to her favoured pink, signifying that she is happy again.
Early in Harry Potter and the Deathly Hallows, Tonks accompanies twelve Order members to take Harry Potter from the Dursleys' home to The Burrow, and before they leave the Dursleys' home, she announces that she recently married Remus Lupin. She flies with Ron, who impersonates Harry using Polyjuice Potion, as a decoy to have Death Eaters thrown off the real Harry's tail.
Later in the book, Remus reveals Tonks is pregnant. She gives birth to Teddy Lupin, named after Tonks's father, who had been killed before the child's birth for being Muggle-born. Remus and Tonks choose Harry to be the godfather. Teddy is also a Metamorphmagus, like Tonks, as seen by his frequent hair colour changes right after birth. When Harry returns to Hogwarts in search of the Ravenclaw relic that Lord Voldemort had turned into a Horcrux, both Tonks and Lupin arrive along with other members of the Order of the Phoenix and Dumbledore's Army. When the Death Eaters attack Hogwarts to get Harry, both of them join the others to hold off the Death Eaters in order to buy Harry time to find and destroy the Horcrux. During the Battle of Hogwarts, Tonks is killed by Bellatrix, and Lupin is killed by Dolohov, leaving Teddy an orphan left in the care of Tonks's mother Andromeda.
Tonks actually arrived after most of the other Order members, having been told by Lupin to stay at her mother's house. It is not actually revealed in the book that Bellatrix kills Tonks. Harry had seen Lupin and Dolohov dueling, while Tonks is last seen trying to find him (she probably knew that Dolohov had slain Remus and that was why she was dueling with Dolohov). Harry finds Lupin and Tonks among the dead bodies in the following chapter. The fact that Bellatrix is the Death Eater who kills Tonks was revealed by Rowling in the Bloomsbury webchat on July 30, 2007, but also suggested earlier in Harry Potter and the Deathly Hallows by Voldemort's suggestion to Bellatrix that she should "prune [her] family tree" given Tonks's supposed desecration by marriage to a werewolf. Tonks also comments that Bellatrix tried very hard to kill her while the Order of the Phoenix was evacuating Harry from No. 4 Privet Drive.
Tonks gets along well with Harry, Hermione and Ginny, acting as an older sister for Ginny, the youngest child and only girl in a family with seven children, and also to Hermione, an only child. Harry is made the godfather of Teddy Lupin in Deathly Hallows; he also saves Tonks and Remus's marriage by confronting Remus when he considered leaving Tonks to protect her and their then-unborn child from anti-werewolf prejudice. Harry plays an active role in Teddy's life after the deaths of Tonks and Remus; in the epilogue to Deathly Hallows it is mentioned that Teddy is a frequent visitor to the Potter home, as he "shows up for dinner about four times a week". Teddy is also close to the other Weasleys, especially to Victoire, whom he was spotted kissing in a train compartment.
Thanks to Wikipedia for the information above.
