Of the two brothers in Supernatural, Sam is often seen as the brains of the operation. Often shown conducting research, working on the lap-top, and figuring out history, Sam provides much-needed assistance when they work a case. In addition, Sam can think on his feet in difficult situations. On top of this, Sam seems more aware of the emotions of others. His empathy or emotional intelligence/smarts is also high.
While we could look at any episode of Supernatural and identify at least one smart Sam moment or two, we chose the following moments that do truly prove how smart Sam is as well as how valuable he is to the family business.
Wards The Trunk Of The Impala
Sam's intelligence was quickly established in the first seasons. Dean has been driving around (and John before him) with a massive amount of weapons in Impala in order to keep the Colt and other items in it safe from supernatural hands.
Drives The Woman In White Into The House
In the very first episode, Sam and Dean investigate a woman in white. While alive and after finding out about her husband's infidelity, she drowned her two children, and then jumped off a bridge to her death. Now, as a ghost, she targets men suspected of infidelity. She even tempts them as if to show further proof of their infidelity or potential to commit it. At her request, they take her home, and after lamenting that she can never go back, she kills them.
She tries to do the same to Sam. Although Sam has never been unfaithful, it doesn't matter because in her mind--all men will eventually be unfaithful. Sam saves himself by driving the Impala and her into the house. Smart, he realized that her biggest fear was to go home and have to face the children that she killed.
Figures Out Molly Isn't Aware She's A Ghost
Sam and Dean go looking for two ghosts in Season 2's Roadkill. One of the ghosts comes running toward their car, asking for help. Sam quickly realizes that Molly doesn't know that she's a ghost.
He determines this quickly and shares it with Dean. Having this knowledge, both gives Sam sympathy for Molly, but also help them know how to work with her.
Senses Jack Isn't Evil
When Jack (Lucifer and Kelly Kline's son) is born, a number of disastrous events occurred. Kelly Kline died. Then Cas was killed. Lucifer tried to find his son. A snare in the fabric of this world led them to see another world, an alternate world that wasn't the kindest. In that other world, their mother, Mary, in a moment of sacrifice helped her boys by staying behind with Lucifer. Also, Crowley died.
So, it is easy to see why Dean would think that Jack could be evil. Add to this, Jack was born a young adult, not a baby. He also possesses a scary amount of power. However, Sam realizes that Jack deserves a chance and was just acting out of fear when he first zapped them with his power. Sam looks beyond the situation and sees more than most.
Figures Out How To Kill The Fear Ghost
Working with Bobby in Season 4, they figure out how to kill the fear ghost that infected Dean. If they don't succeed, then Dean will die. While Bobby provides the needed research, that a ghost born of fear needs to be killed with fear, Sam figures out how to do it.
Cut to Bobby saying, "This is a terrible plan." Luckily, a terrible plan worked, and Dean lived to see another day.
Finishes Rowena's Spell
Season 15 makes Sam out to become a witch. It seems that his previous friendship with Rowena led to him learning magic from her. Apparently, he's a quick study (which doesn't surprise us). He finds a spell that Rowena had been working on to restore Mary back to corporal form after Jack (without a soul) had blasted Mary dead. The spell was almost finished. Sam was able to finish and do such a complicated spell to bring Eileen back to life is a testament to his intelligence.
Tricks The Poker Warlock
In Season 5, a warlock holds a very special poker game where the attendees gamble with the years of their lives, not money. If they win, they can win back their youth. If they don't, they rapidly age and could die. Bobby decides to play, and he loses 25 years. Dean decides to help get Bobby back his years, and he loses even more of his own years. Both Bobby and Dean don't want Sam to play, thinking Sam to be a horrible poker player.
But Sam is impressive and tricks the warlock by acting like he loses his cool when Dean is brought up, playing into the warlock's assumptions. In the end, Sam wins all the years back, and proves that he is a good poker player due to his intelligence. He can read his opponent, a skill both Bobby and Dean didn't have.
Conducts A Reverse Exorcism
In Season 8, upon learning that the Prophet Kevin's mom is being held hostage by demons, Sam and Dean go to save her. One of the demons had inhibited her good friend and goes to leave; the black smoke of its soul exits.
Sam stops it by conducting a reverse exorcism and making the demon soul go back into the body it had left. When Dean asks how he did it, Sam casually says (almost with a shrug) that he just said the exorcism backwards.
Outsmarts Famine, One Of The Horsemen
In Season 5, the deadly horsemen walk the earth, and Sam and Dean try to defeat them. Famine encourages Sam to drink demon blood and to kill the demons currently protecting the horseman. Sam starts to do it, exorcising the demon souls out of their human vessels. However, he stops, and we see the dark cloudy souls at the floor. Famine then eats the souls, and tells Sam that Sam doesn't have the power to kill him.
Sam thinks on his feet, saying, "You're right, but it will work on them." By exorcising the demons that Famine has eaten, the demons that are now inside Famine, Sam effectively kills Famine.
Learns Of Chuck/God's Intent In Having Dean Kill Jack
In Season 14, Chuck/God presents the brothers with a horrible mission--to kill Jack with a special gun that Chuck/God invented. The only catch--whoever shoots it will suffer the same wound. Jack, now without much a soul, recently killed Mary Winchester. So, Dean believes that Jack must be put down. Chuck/God gives him a way to do it.
Obviously, something sounds off with the scenario, and all throughout the episode, Sam is aware that something doesn't feel right. When he notices the way Chuck/God looks at Dean pointing the gun at Jack, he says, "Are you enjoying this." In the end, Sam figures out that Chuck/God has been playing their whole life for his own enjoyment. In a quick minute, Sam picks up the special gun and shoots God/Chuck. While it doesn't kill God/Chuck, the shot weakens him, giving the Winchesters a chance against the most powerful villain they have ever encountered.
