In the words of Bobby Singer, "family don't end with blood." Family was at the heart of Supernatural for the duration of the show's fifteen seasons. The Winchesters met many people along their journey who were there for them through thick and thin, only proving Bobby's iconic line.

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From Charlie, Jody, and Garth to Ellen, Jo, and Bobby, the boys had plenty of allies over the years who became nothing less than family. But what about their biological parents? We had a little insight into their parents' pasts and a small glimpse of the events that led them down the hunting path, but not a lot in the grand scheme. With a Supernatural spin-off finally given the green light, fans will see a more thorough look into the lives of John and Mary Winchester pre-SPN.

Season 1, Episode 1 - "Pilot"

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"Dad's on a hunting trip. And he hasn't been home in a few days." That one sentence had us hooked from the first episode. What better place to start than the one that started it all? The episode opens with a family in their home as two children are about to head to bed. That family was the Winchesters, in their home in Lawrence, Kansas, twenty-two years ago, moments before the tragic paranormal event that took Mary's life and left her burning on the ceiling.

Supernatural's pilot may not have delved too deep into the Winchesters' backstory prior to Mary's death. However, it was the beginning of the adventure that millions of people came to love over its fifteen years on the CW. The episode remains the first insight into the tragic events that led the boys to who they became, revealing what happened to Mary and John's hellbent revenge on killing the demon responsible. "We've got work to do."

Season 14, Episode 13 - "Lebanon"

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Image via The CW

We knew Supernatural's 300th milestone was bound to bring out the big guns, based on the genius it brought with its 200th episode four years prior. After twelve years, John Winchester returned. In an attempt to get the archangel Michael out of Dean's head, the latter used a Chinese pearl capable of granting the owner their greatest wish but instead accidentally summoned his dad forward in time.

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From Sam and John's heartfelt chat to that Winchester family dinner, Season 14's "Lebanon" made for some iconic scenes that Supernatural fans will remember forever. But considering the premise of how the SPN story began, the reunion between John and Mary may be one of the most memorable. Sadly after things around them started changing due to the altered timeline, the boys were forced to say goodbye to their father. This episode may not delve much into the lives of John and Mary, but seeing the Winchesters together again gave a heartbreaking bittersweet look into what could've been.

Season 6, Episode 1 - "Exile on Main Street"

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Season 6 is controversial among fans, with some liking it and others not so much. Wherever you stand, the season opener reintroduced us to Mary's father, Samuel Campbell, now inexplicably alive and well, as well as a few other members of the family on their mother's side. The last time we saw Samuel was in season four after Cas sends Dean back to 1973.

Samuel died after Yellow Eyes possessed and stabbed him while under his control, so fans were surprised to see him back. The Campbell family storyline didn't go past Episode 16 of the show's sixth season, and it's safe to say that many fans weren't sad to see them go. Despite varying opinions on their story, the episode and the first half of the season gave us another glimpse into the Campbell/Winchester family members and delved deeper into their earlier lives.

Season 8, Episode 12 - "As Time Goes By"

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A blast from the past. This season eight episode introduced us to another Winchester family member, only this time from 55 years in the past, in 1958. Sam and Dean's grandfather, Henry, makes a surprise visit when he blasts through the closet door of the boys' motel room, demanding to know where John Winchester is.

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"As Time Goes By" served as the first insight we had into John as a little kid and his father's past with The Men of Letters. Henry traveled forward in time to keep a mysterious box with the Men of Letters crest engraved on it away from Abaddon. Not only did the episode reveal that both John and the boys are legacies to the Men of Letters, but the box contained a key to a bunker containing every MoL secret and then some. Until this episode, the boys were under the impression from John that Henry walked out on him when he was young, but in reality, Henry never left 2013 after sadly dying in his grandson's arms at the hands of Abaddon.

Season 5, Episode 13 - "The Song Remains The Same"

The Winchesters
Image via The CW

"Team Free Will. One ex-blood junkie, one drop-out with six bucks to his name, and Mr comatose over there." The angel Anna travels back to 1978 to stop Mary and John from conceiving Sam to prevent him from becoming Lucifer's vessel. No vessel, no Lucifer, no apocalypse, right? Wrong. Cas takes himself, Sam, and Dean back to the same time to stop her. While there, Dean and Sam try to convince Mary to leave John, so they are never born, but she reveals it's too late as she is already pregnant with Dean.

"Free will's an illusion, Dean." Michael tells Dean that from being born to falling in love, every random act of chance wasn't chance but a plan playing out perfectly, insinuating that everything that has happened to their parents is destiny. Michael wipes John and Mary's memories, allowing them to forget this encounter and live life as she wanted without knowing the truth of what's to come. This episode delved further into the path their parents were put on and the events leading to that fateful night on November 2nd, 1983. And thus, Team Free Will was born.

Season 4, Episode 3 - "In The Beginning"

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Season 4's third episode, "In The Beginning," revealed that Mary had always been in the hunter's life, as her father had brought her up with the knowledge of what lurks in the shadows.

"Hello, Dean." Castiel sends Dean back to 1973 Lawrence, Kansas, with a vague warning to "stop it," where he meets his young parents and his grandparents, who are also hunters. He discovers the truth that Azazel made Mary an offer to resurrect John if she gave permission for him to do something that he wouldn't reveal in ten years. That something? Give Sam the taste of demon blood. The episode was the first look back into the lives of John and Mary early in their relationship, followed by the exact moment everything went haywire for the Winchester family.

NEXT: 'The Winchesters': Trailer, Cast, and Everything We Know So Far About the 'Supernatural' Prequel