Anna Milton

Background
Anna Milton was a high-ranking angel of God (stationed on earth for 2000 years), before she defied orders, cut out her grace, and fell to Earth. She fell to Ohio and impregnated a housewife named Amy Milton, who before was unable to get pregnant, and became human. Anna was raised by Amy and her husband Rich, who was a deacon. Her grace also fell to earth in a field in Kentucky, which upon contact made the field flourish. The grace created on oak tree in six months that looked as if it were centuries old.

When Anna became two and a half years old, she would panic anytime her father, Rich, came near her. She kept telling Rich that he was not her real father. She would also say that her real father was angry at her and was going to kill her. Her parents took her to child psychologist and she got better. As Anna aged, she forgot more and more about her angelic past until she was completely unaware of it. She grew up normally until she started hearing voices in her head on September 18, the day Dean was resurrected. The first message she heard was "Dean Winchester is saved". She was then admitted to a psychiatric ward, deemed as having a mental illness when in fact, she was hearing angels communicate.

Season 4
In "I Know What You Did Last Summer", Anna is in her room at the psychiatric ward with a psychologist asking her questions. She tells the psychologist that the apocalypse is coming revealing that she knows about the 66 Seals and Lilith. Later that day, a nurse comes into her room to give her medication. Anna immediately becomes frightened due to the fact that the nurse is possessed by a demon and she can she its true face. When the demon starts walking towards her, she telekinetically throws a dresser at the demon. The demon is knocked unconscious and Anna escapes the ward.

She decides to hide in her father's church. When the Winchesters look for her at the church, she tells them that she feels like she knows them because the angels talk about them all the time. She reveals to the brothers that she started hearing the angels on September 18, which the brothers immediately recognize it as the day that Dean was brought back to life. She then asks the brothers about her parents, but before they can answer Ruby arrives. She tells them demons are coming for Anna, but it's too late and Alastair arrives. While the brothers fight him, Ruby takes Anna to safety.

When they're reunited with the Winchesters later, Anna asks if she could call her parents so they won't worry about her. They tell her that her parents were killed by demons. She becomes very upset, but stops crying when she senses that someone is coming. The brothers place her in another room while they prepare to take on the threat that she sensed. The Winchesters are surprised to see Castiel and Uriel demanding that they give them Anna and stating that she must die.

In "Heaven and Hell", while the Winchesters and Ruby take on Castiel and Uriel, Anna creates a blood seal that banishes the two angels. The four of them go to Bobby's house so Anna can be protected in the demon panic room. Sam gains more background information on Anna and learns that she had to see a shrink as a child because she kept telling her father that he wasn't her real father and that her real father wants to kill her. Dean brings Pamela Barnes to Anna to figure out more about her past. Pamela puts Anna in a trance, but she soon starts to panic saying that father is going to kill her causing the lights to explode. When she's brought out of the trance, Anna remembers that she was once an angel.

Anna explains that she is a fallen angel and became human by ripping out her grace. Ruby realizes that's why she being pursued by demons as she was an angel who could "bleed" and be tortured for knowledge. Anna says that's also why the angels want her dead plus she had disobeyed, which is an angelic crime punishable by death. Anna reveals to everyone that she plans on getting her grace back. While Sam searches for where Anna's grace landed, she and Dean talk. He asks her what the angels want with him, but she tells him that she doesn't know and that the angels don't talk about it. Then Dean asks her why did she become human. She tells him that she loves all the emotions you feel as a human, the good and bad. She then goes on about how even though the angels were "perfect", they're basically statues and how miserable she was being stationed on Earth just watching and waiting for orders from God, who she had not even seen. Dean relates her experience to that of him and his father. Their conversation is interrupted by Sam, who figured out that Anna's grace landed in Kentucky. When they arrive in the field it crashed in, Anna walks to the tree that was created by the grace to discover it's gone. Later on, she says Dean that she isn't worth protecting for she committed the same crime as Lucifer and that she should pay. Dean replies that everyone has done things that they have to pay for. She then finally tells Dean that she knows what he did in Hell and that he should forgive himself and that it wasn't his fault. She then kisses him and the two have sex in the back of the Impala.

Later, Anna and the Winchester boys are confronted by Castiel and Uriel. She realizes that they found her through Dean by threatening to kill Sam. They are interrupted by the arrival of Alastair, Ruby, and two other demons. While Uriel is distracted by the demons, she is able to grab her grace, which is around his neck, and regain it. As her grace enters her body, she tells the Winchesters and Ruby to shut their eyes. Her body is destroyed releasing a bright, white light and she becomes an angel once again.

Anna returned briefly, later in the fourth season, where she killed Uriel to save Castiel. In When the Levee Breaks, Anna confronts Castiel briefly, about why he released Sam. Castiel tells her that "she really shouldn't have come", right before she is taken away by two angels.

Season 5
In The Song Remains the Same, Anna returns going into Dean's mind and appearing to him in his dreams. She tells Dean about how Castiel sold her out to the angels and that she's been a prison in Heaven. She tells Dean that the angels are looking for her and asks Dean meet with her at a warehouse.

While waiting at the warehouse, she is confronted, not by the Winchesters, but by Castiel. He tells her that although the Winchesters trust her, he doesn't and knows that no one escapes Heaven implying that she's working for the angels again. Anna retorts and says that no one sent her and that she escaped. She then tells Castiel that Sam must die. Castiel says that won't work since Lucifer would resurrect him, but Anna says that she plans on scattering Sam's cells across the universe so he can't. Anna tells Castiel that he's changed after he tells her that he won't allow her to kill Sam because he's his friend. Castiel then threatens Anna that if she comes after Sam that he will kill her. After being threatened she teleports away.

Anna then goes to the 1978 to kill John and Mary Winchester before Sam can be born. She tries to kill them by posing as John's boss and getting John to come over to the garage that he's working at knowing that Mary and the Winchester brothers would come for him. She overpowers John, Mary, and Dean but she gets banished by Sam using the blood seal. Anna then enlists the help of Uriel of that time. She tells him that people she wants him to kill will kill him in the future and that she's allowing him the chance to kill them first. With Uriel's help, Anna manages to stab Sam in the stomach and kill him. Just before she is about to kill Mary, she is approached by John, who is being possessed by Michael. Michael lays his hand on Anna, setting her ablaze and killing her. It was never revealed before her death, whether or not she was working for angels like Castiel suggested or if she was telling the truth and that she escaped Heaven and decided of her own free will to kill Sam.

Powers
Even without her grace, Anna seemed to retain some her angelic power: After reclaiming her grace, she regained the rest of her abilities that are shared among all angels:
 * Telekinesis - Anna was able to telekinetically throw a dresser at a demon-possessed nurse
 * See Demons - Anna was able to see the true face of a demon possessing a nurse
 * Precognition - Anna seemed to be able to see into the future and drew what she saw whille she was in psychiatric ward
 * Hear Angels' True Voices - Anna could listen to angels' conversations
 * Magical Knowledge - Although she didn't know what it is was, she knew how to create a blood seal that would banish angels temporarily
 * Enhanced Strength
 * Extreme Endurance - When Mary Winchester stabbed her with a crowbar, she seemed unfazed only spitting up a little bit of blood
 * Teleportation
 * Time Travel - Although she successfully traveled back to 1978, as soon as she arrived she spat out blood and became unconscious
 * Exorcism - Although she never displayed this ability it's expected that she regained it after regaining her grace returned to her since both Uriel and Castiel were capable of this ability and she at one time was their superior
 * Angelic Possession - After she regained her grace, her human body was destroyed. After calling in some favors, she had it recreated so she could possess it and use it as her human host

Name
Her surname Milton alludes to the famous poet John Milton, whose epic work Paradise Lost influences Supernatural, particularly in later seasons concerning angels and Lucifer.

Season 4

 * "I Know What You Did Last Summer"
 * "Heaven and Hell"
 * "The Rapture"
 * "On the Head of a Pin"
 * "When the Levee Breaks"

Season 5

 * "The Song Remains the Same"