|“||Hello, my shadow-self.||”|
They are known as "Stilas" by fans.
Not much is known about the connection they share due to Stefan being Silas' doppelgänger. Silas referred to Stefan as his distant grand-nephew, suggesting that Stefan's bloodline originated from one of Silas' siblings.
Qetsiyah mentioned that there were other doppelgängers of Silas prior to Stefan's birth. It was later learned that Silas had another doppelgänger after Stefan named Tom Avery, the only other known doppelgänger in his line.
Throughout The Vampire Diaries Series
In Season Four, Stefan worked with many of the members of the Mystic Falls Gang, as well as Rebekah Mikaelson, in order to find Silas' tomb so they could retrieve the cure for immortality that was entombed with him, as they believed there was an unlimited amount of the cure there. However, though Silas was awakened while they were all on the island, and the cure was stolen by Katherine Pierce, Stefan would not end up officially meeting Silas until Pictures of You.
In Bring It On, Stefan called Damon, who was on his way out of town with Elena, to inform him that Mystic Falls' hospital, along with several other hospitals in the nearby area, had their entire blood bag supply stolen. Stefan came to the conclusion that Silas had followed them back to Mystic Falls, and had stolen the blood to feed on in preparation for a big plan.
In Pictures of You, Silas appeared as Stefan to blackmail Damon into helping him with his plan to essentially get rid of the Other Side by permanently dropping the veil between it and the living world. Conversely, Stefan had a similar encounter with Silas, who appeared to him as Damon, which resulted in Silas stabbing him in the stomach with a stake.
In The Walking Dead, when Silas found out Bonnie's plans to deceive him, he created illusions to take the form of several of her friends, including Stefan, to demonstrate that he is much stronger than her.
In Graduation, Stefan brought what he believed to be Silas' petrified body in a body bag to Steven's Quarry in order to lock him in a large safe and throw it at the bottom of the lake to ensure he would never bother them again. However, when he opened the bag to put him in the safe, he found that Silas' body wasn't there. Stefan looked around in confusion for a moment until Silas appeared behind him, having taken the form of Elena. He then explained to Stefan that he was able to overcome the spell that petrified him after the death of the witch who cast it. Silas also added that because he ingested the immortality spell that he and Qetsiyah created over two thousand years ago, he was unable to die, so Nature found a balance by creating a version of himself that could die—a doppelgänger, or a shadow-self. Stefan immediately assumed that Silas was the progenitor of what was known as the Petrova doppelgänger line, but Silas corrected him by taking his true form, which was identical to Stefan, revealing that Stefan, too, was a doppelgänger of Silas. Stefan was so taken aback by this revelation that Silas was easily able to stake him in the stomach, throw him in the safe, and shove the safe off the cliff into the water below. Stefan and the safe sank to the bottom of the lake, where he quickly drowned. He then spent the next four months trapped underwater in the safe, where he suffered through the same cycle of drowning and being revived over and over.
In Original Sin, unknown to Silas, Stefan had been rescued from the quarry by Qetsiyah, who had returned from the Other Side during the time that Bonnie had lowered the veil to the dimension, as the hunters of the Brotherhood of the Five, the order created by her descendant in the 12th century, had failed to kill Silas as they were intended. Qetsiyah, now going by the name of Tessa, explained to Stefan the story of her history with Silas, and used magic to link Stefan to Silas so that she could disable his psychic abilities in order to prevent him from using his telepathy to learn of and intervene in her plans. However, in linking Stefan to Silas, the spell caused Stefan excruciating pain to the point that he lost all of his memories.
In Monster's Ball, Silas tracked Damon down at the Whitmore College Historical Ball that was held at the college and told him that he needed him to "kill" Stefan before explaining this plan, which would allow them to figure out what Tessa had used as the anchor that bound the spell that created the Other Side. He also explained that Damon needed to snap Stefan's neck, which would temporarily disrupt the spell that was blocking Silas' psychic abilities so he could use telepathy to figure out where the anchor was hidden. After Stefan had awoken from healing his snapped neck, he was so furious at Silas and Damon's plans that he tracked Silas and Tessa down to out him; since Stefan was awake, Silas' psychic abilities were disabled once again, putting him in the position to be petrified a second time by Tessa using the power of her talisman.
In Death and the Maiden, Silas received a call from Stefan, who immediately informed him that he had captured Silas' true love and anchor to the Other Side, Amara, as a hostage, and threatened to run off with her and keep her alive indefinitely to ensure that they both would never be able to die and spend eternity together in the afterlife. This ploy succeeded in luring Silas out into the woods, where he found Amara bound to a tree. While Silas was preparing to slit Amara's throat to kill her and destroy the Other Side, Stefan intervened, and the two began to fight. Silas lost his knife at some point in the fight, and though Silas did briefly incapacitate Stefan with a pain infliction spell, Stefan was able to overpower it and throw the knife at Silas, hitting him in the chest and killing him before Amara had the chance to die. Despite Stefan's belief that killing Silas was what he needed to do to help him deal with his post-traumatic stress disorder from his four months spent drowning in the quarry, Stefan continued to be overwhelmed by the memories caused by Silas' actions.
- Elena/Silas: Don't bother. I'm not there.
- Stefan: Silas. You were stone. They saw you. The spell worked.
- Silas/Elena: That's the funny thing about spells. They're bound by Nature. Nature demands balance, so every spell has a loophole. The spell that turned me to stone, it was bound by a witch, a living witch. So when that witch died, the spell broke.
- Stefan: Bonnie? Bonnie's not dead.
- Elena/Silas: It doesn't matter, does it? And here's where the mystery of me comes full circle. I created the immortality spell two thousand years ago. I can never die. So nature needed to find balance - a version of me that could die. A shadow-self, a doppelgänger.
- Stefan: So, this is finally your real face. You're another one of them?
- Elena/Silas: Not exactly.
- (He shows Stefan his true form-- a face identical to Stefan's)
- Silas: Hello, my shadow-self.
- (Silas walks towards Stefan and stakes him in the stomach)
- Silas: Do you have any idea what it's like to starve for two thousand years?
- (Silas locks Stefan inside a safe and pushes it into the quarry)
- -- Graduation
- Damon: (to Silas) Where's Stefan?
- Silas: He's suffering. Like I suffered.
- -- I Know What You Did Last Summer
- Ironically, Stefan was enemies with Silas, much like fellow doppelgängers Elena and Katherine were enemies.
- Stefan finally got his revenge on Silas and fatally stabbing Silas after he had taken the cure to become mortal again.
- Tom Avery is the doppelgänger of Silas and Stefan, who is also dead.
- He was also the only doppelgänger who wasn't aware of his supernatural origins.
- Also, as far as we know, Tom never got to meet any of his fellow doppelgängers or their progenitor.
- Both ingested the Cure and died permanently shortly after taking it.
- Stefan murdered Silas shortly after Silas took the Cure from Katherine Pierce.
- Stefan sacrificed his own life to stop Katherine from destroying Mystic Falls shortly after being cured.