In Prophet and Loss, Dean reveals that the book Billie gave him reveals that the only solution is for him to trap himself and Michael in a Ma'lak Box and it gave him directions on how to create one.
He then explains the wager: Death tells Dean to get the ring, put it on, and be him for a day.
In the library, Billie tells Dean that he has already killed her when he nicked her with the scythe, and reveals she is not behind the people disappearing before telling Dean she only wants one thing before she dies -- to kill him.
Tessa is a reaper, guiding the recently deceased to the afterlife. She first appears to Dean Winchester after his horrific car crash which left him in a coma.
She can only be visible to people who are about to die or the dead (Ghosts). Other beings such as angels, demons, and Death can see Tessa. She can apparently become visible at will to humans as Dean was able to see her when he captured and interrogated her.
On multiple occasions, Dean has shown that - of all the women he has slept with - he truly loves Lisa. Before and during the first few episodes of, season 6, Dean lives with the Braedens for a full year, living an "Apple Pie" life. Dean's nickname for Lisa is "Lis'".
Before dying, John tells Dean, if he can't save Sam, he'll have to kill him, should he become evil.
Meet Sin, the half mortal daughter of the infamous Angel of Death, the Grim Reaper. Grim hasn't exactly been father of the year material when it came to raising his daughter.
At the end of the series, Will marries Tessa, having two children, Lucie and James, with her. Jem has to separate from both of them now that he is a Silent Brother, however, when Will dies in 1937 of old age, his family and friends, Tessa, and Jem are all by his side.
He is also known as the Pale Horseman whose name is Thanatos, the same as that of the ancient Greek personification of death, and the only one of the horsemen to be named.
In Castiel's final moments, he smiles through his tears as the Empty takes both him and Billie, saving Dean. Castiel's final words are "Goodbye, Dean."
After Despair, her final appearance in Supernatural aired, Lisa shared a behind the scenes set of pictures on her twitter, revealing that she was visibly pregnant during the filming of Despair with "a little baby reaper on the way."
Dean spent a year in purgatory before being able to escape with the help of his vampire friend, Benny, whom he met in purgatory.
According to Death neither he nor God could remember which of them was older. However, when the Darkness was released from her prison, Amara claimed to Dean Winchester that she didn't know who Death was, and vice versa, which firmly established that God and the Darkness were older than Death.
Finally, Bobby reveals what message Death gave Karen at the cemetery: that Death was after Bobby in order to stop him from helping the brothers in their fight against the apocalypse. Although it seemingly went by fast, “Dead Men Don't Wear Plaid” was one of season five's best episodes.
While trying to cope with his impending death and make the best of his final year, Dean begins to start hunting the freed Demons. Meeting a seemingly helpful demon Ruby, Dean learns that he too may become a demon himself if he burns in Hell too long.
After 3 - Chapter 286.
Tessa has a condition called, "cervical insufficiency", meaning that her cervix is shorter than the average woman. Her condition made it difficult for her to get pregnant and carry a child to full-term, which caused her to have a miscarriage.
Kim Tae-woo: Grim Reaper No. 444.
Grim falls in love with a Gothic woman named Malaria, who also falls for Grim not knowing that he is the real thing.
Like A Virgin is the 12th episode of Season 6.
Dean killed Benny, returning him to Purgatory where he led Sam and Bobby out but remained behind to cover their escape. Dean returns from Purgatory carrying Benny's soul in his arm and travels to Benny's grave in Louisiana. There, Dean performs a ritual, restoring Benny's soul to his body and resurrecting him.
Sam's supernatural abilities are the result of him being fed Azazel's demon blood while he was an infant. Sam exhibits signs of precognition throughout the first season, manifesting as dreams of others' deaths and later as visions.