Since its first season, Supernatural's main characters experienced death and insurmountable pain, but also the greatest victories. Aside from their obvious fights with the supernatural realm, Sam and Dean went through deep emotional issues and addressed many conflicts over the show's 15 seasons.
Sam and Dean wanted many things in season 1 of the series. While not every dream that they had came true by the finale, a lot of their greatest desires and needs were ultimately fulfilled.
Dean Mending His Relationship With Sam
In his final moments, Dean strikes a tearful chord when he reveals the truth about the night he visited his brother at Stanford. The truth is that Dean waited outside of Sam's building for hours, afraid that Sam would tell him to "get lost or get dead."
By the end of the series in Season 15, the brothers' relationship is stronger than it once was. Years before, Sam left for Stanford frustrated at the path that John put them on. But, John wasn't the only one Sam left. Sam left both John and Dean to live his own life, rightfully so. However, Dean wanted to have his little brother back in his life.
John Apologizing To Sam
This was a huge deal for Sam. When his dad died in Season 2, Sam went through a wide range of emotions, including guilt. They spent John's final moments arguing, as per usual. In Season 14, Sam tells his dad he only thinks about how he "never got to say 'goodbye'" to him before the Yellow-Eyed demon killed him.
When John apologized to Sam (and vice versa), Sam was finally able to get closure on their relationship. Prior to this, he struggled to wrap his head around the situation with his dad. Even after they shared a positive moment in Season 1, when John revealed that he spent Sam's college fund on ammo, Sam still didn't get a proper apology from his dad until Season 14.
Sam & Dean Getting To Know Mary
Since the pilot episode, one mention of their mother would upset the brothers, especially Dean. Sam tells Dean that killing the Yellow-Eyed demon wouldn't bring Mary back, which angers Dean to say, "Don't talk about her like that."
The brothers later got what was always wanted, and that was officially getting to know their mother as a person. Since Sam never really knew his mom, he later had the chance. Dean, however, always wanted the chance to spend time with his mom, and he finally did in several episodes focusing on Mary Winchester.
Saving People By Hunting Things
Dean initially wanted to "raise a little Hell" by eliminating all of the evil supernatural beings from earth. Although Sam originally had an expiration date for his hunting days, he soon got on board with his brother to save innocent lives from monsters.
From all the evil vampires, witches, ghosts, demons, angels, and even a God who wants to destroy the world, the Winchester brothers accomplished much more than saving a few people. Dean didn't envision them saving the entire planet, but he knew that their mission was to be the unsung heroes—and he wanted this.
Sam Getting His "Normal, Apple Pie Life"
In Season 1, Sam was on the path to the show's so-called "normal life." Getting married and starting a family of his own was something Sam wanted, as was attending law school. When Dean challenged him for wanting the "normal, apple pie-life" in the pilot episode, Sam said he viewed it as a safe life.
Clearly he gave it up for the hunting life, until he lost his big brother in the series finale. It was revealed that Sam had continued the Winchester family business, but managed to have his own family later in life, even naming his son Dean.
Killing Yellow Eyes, Avenging Mary's Death
Since the pilot episode, it's obvious that the Winchester family business started because of Mary's death. Losing their mother traumatized John and his sons. So, all the Winchesters knew was vengeance.
After Jessica was murdered, Sam then became vengeful and only wanted to bring down the demon that killed her. The three Winchesters were finally able to kill the demon at the end of Season 2. Obviously, this didn't mark the end of the road they were on, but they accomplished their primary objective in killing Mary and Jessica's murderer.
The Winchesters Finally Being Together
Who would have thought the whole family would get back together? It certainly was a beautiful sight to see in Season 14 when the entire Winchester family of both parents and sons were in the same room together, laughing and having dinner.
The first season showed the strong brotherly bond that Sam and Dean started to form without their father. Even after finding him, they didn't have much time with their dad. The brothers never knew what it was like to have their family full again until Season 14, but it was always their dream since the beginning of the series. They just didn't realize that the chance to reunite would come.
Getting An Actual Home
Although it's not explicitly stated, the brothers wanted a home since Season 1 in different ways. Sam was the one who experienced a home of his own in college, while Dean never really had a home.
What the brothers wanted for a long time was a place to return to, which they didn't have when they were growing up. The only difference was that the brothers had different ideas of what that was. The motel rooms and constant traveling erased any familiarity of what a home base would feel like. Thankfully, they got the Men of Letters bunker in later seasons, which became their home.
Finding John
Aside from finding and killing Azazel, Sam and Dean were also intent on finding John since the pilot episode. After all, Dean's infamous line, "Dad's on a hunting trip and he hasn't been home in a few days," kickstarted the show into high gear.
At the end of Season 1, the brothers stumbled across their dad when he decided he could see them again. Of course, John then wrestled with the idea of them all sticking together, as he thought it weakened them. Nevertheless, John came around to the idea of fighting evil together and stayed with his sons through the entire first season.
Sam Forgiving Himself
Sam struggled with guilt for a long time. Once Jessica died, he blamed himself for her death. Sam then blamed himself for the deaths of others around him.
Sam's guilt was further emphasized when the brothers had to defeat Bloody Mary, when Sam's remorseful, self-loathing side emerged in a mirror reflection. It was Dean who wanted his little brother to forgive himself for his girlfriend's death. Eventually, Sam learned to forgive himself for the things he couldn't control. This was something that he didn't know he wanted so badly, but thanks to Dean, he reached a healthier point in life: being at peace with himself.