Supernatural is a very entertaining series. I first caught the show sometime during the third or fourth season (the show where the brothers Dean and Sam Winchester are placed in an alternate reality where they don't know one another -- Dean is a corporate executive and Sam is a custodian in the same building) and became hooked after viewing that single episode. Now I've decided to go back and start watching the series from the initial episode.
The theme has pretty much remained the same: Dean is the older brother, more of a wisecrack and passionate about killing supernaturals while Sam is the younger brother, no less passionate about the "family business" but more reflective about what is being killed and why. The first episode draws Sam back into the family fold after Dean shows up and says "Dad has gone hunting and hasn't returned." Sam is away at college and preparing to sit for his pre-law school exams. He reluctantly joins Dean and, by the episode's end, a tragic event forces Sam to abandon post-secondary education and return to the life that he tried to escape.
The catalyst for their lifestyle occurred when Dean was young and Sam just an infant. One night their mother is burned alive while pinned to the ceiling by a supernatural invader who invaded Sam's nursery. Their father tells Dean to take Sammy to safety and from that point on, as you learn in flashbacks, John Winchester is determined to find and kill the monster responsible for his wife's death. While Dean never questions his father's actions, Sam is troubled by them and ultimately has a falling out with his father right before Sam leaves for college.
The two main characters bicker and disagree just like brothers do in real life. Of course, there is an added element of tension because these two brothers are in the family business of killing demons, shape shifters, reapers, vampires, etc. But the dialogue is entertaining, there is often an element of comedy in each episode, and the love between the two brothers comes through despite their differences. Their father makes an occasional appearance and while you don't doubt he loves his sons, Dad's personality is a little off-putting. Still, he is the catalyst for the tension between Dean and Sam: Dean is the obedient son (until he isn't) who never questions his father and Sam is the rebel (until he isn't) who wants to know the reason behind their father's reclusiveness and his desire to keep his sons in the dark. And just like real brothers, their attitudes towards, and obedience to, their father changes depending on the circumstances.
The show can be violent and as the episodes progress, they appear to get bloodier and gorier but not in every episode. The brothers meet many people on their travels across the country (they constantly live in motels, using fake credit cards to pay for rooms, gas and food), but cannot be open and honest about why they appear at crime scenes. They are experts at portraying undercover police officers, FBI agents and medical doctors, which explains their presence after grisly killings, mystery illnesses, or unexplained disappearances. The season finale is a true cliffhanger and the viewer will want to know what happens to the Winchester men. Five stars!