Ghosts As An Obstacle
In the first season of , there are several episodes in which the brothers have to fight ghosts. In these early years, ghosts were far more of a task than they became later on, with Sam and Dean having to fight harder to overcome the apparition.
Ghosts were far less common after Sam and Dean had to start battling gods, demons, angels, and even the Devil and God. Though there was occasionally a ghost they dealt with, it was either far easier for them to battle these undead or there was a unique spin on the same ole to make them more formidable.
Fighting Demons
There were many that were either serious threats to the brothers or surprising allies. However, in the first season, the brothers were very fearful of demons and had to use far different tactics to kill them (or send them back to Hell).
Before demon-killing knives and bullets, and Sam and Dean took on dozens of demons at once with little issue, demons were a more fearsome conflict. The brothers used the word “Cristo” to make a demon show its true form, and they had to perform an exorcism to send demons back to Hell. In later seasons, they don’t use either of these methods, and demons are waved off as mere nuisances instead of dangerous villains.
Sam’s Ambitions
At the beginning of this story, Sam has no interest in the family business and wanted to live a normal life after going to college. However, as time went on he showed less of an interest in pursuing a “normal” human life.
In the first season, Sam only agrees to go back to hunting after the demon Azazel kills his girlfriend Jessica in the same way it killed his mother. While he could have gone back to school after overcoming this demon, he continued to fight with Dean and stop dark forces from overtaking the world. It’s only after Dean’s death in the finale that Sam finally decides to settle down and build a happy life.
Dean’s Dedication To John
in , making the older son far more devoted and connected to his father. While Sam is the rebellious son, in season one Dean is the one that wants to obey their father’s orders no matter what.
In later seasons, however, Dean begins to question how his father raised them and the kind of effect it had on him and his brother. While season 1 Dean is blinded by wanting to impress his father and earn his love, older Dean understands that their relationship was actually quite toxic.