Scott and Stiles' close, unwavering friendship is known to be the main relationship in the entire Teen Wolf series, and though the two have gone through rough patches in the time they've been friends, they always come through it in the end with their bond even stronger than ever. They have been best friends at least since early childhood, and have been said to be inseparable by their respective parents, teachers, and mutual friends alike.
After Scott was bitten and turned into a Werewolf by Peter Hale in Season 1's Wolf Moon, Stiles became his closest confidante and was the main factor in helping Scott retain his humanity as he learned how to control his lycanthropy, along with help from Scott's then-girlfriendAllison Argent. In time, Scott and Stiles formed a two-person pack that would ultimately become the foundation for the McCall Pack, which grew to include nearly a dozen people, both supernatural and human, who have come and gone throughout the seasons. The two worked as a pair, with Stiles as the "brains" and Scott as the "brawn" in order to solve and deal with supernatural threats such as Peter's reign as Alpha, the Kanima, the Darach, and the Alpha Pack, gaining help from their friends Allison, Lydia Martin, Derek Hale, and Isaac Lahey, among many others. While under the influence of wolfsbane poisoning, it was Stiles who convinced Scott not to kill himself by setting himself on fire due to his belief that the constant death and harm caused to those around him was directly caused by his existence.
Throughout the second half of Season 3, Scott did everything in his power to save Stiles from his possession by the Nogitsune, and no matter how many people told him that the only way to prevent the deaths of innocent civilians was to kill Stiles, Scott refused to believe that Stiles couldn't be saved and ultimately found a way to free him from his possession. Scott and Stiles continued to protect and defend each other through other supernatural threats throughout the following seasons. Although their friendship was briefly broken due to the manipulations of Theo Raeken, it didn't take long before Scott and Stiles were working together again, eventually reconciling and teaming up once again to reunite the McCall Pack. Since Scott, Stiles, and the rest of the pack defeated the Beast of Gevaudan, the Dread Doctors, and Theo, Scott and Stiles' relationship is stronger than ever.
In Season 6, Stiles was abducted by the Ghost Riders of the Wild Hunt and was subsequently erased from existence, but even despite the fact that Stiles was removed from the memories of his loved ones, Scott, along with Lydia Martin and Malia Tate, quickly figured out that something was wrong based on the gaps in their memories. Scott then dedicated himself to figuring out who Stiles was, going so far as to nearly freeze to death in an attempt to trigger his repressed memories in hopes that by doing so, he could open a rift and bring Stiles back. The combined efforts of Scott, Malia, and Lydia eventually did just that, and Stiles played a major role in helping the pack defeat Garrett Douglas and the Ghost Riders. Afterward, when Scott, Stiles, Lydia, and Malia all graduated from high school, Scott and Stiles reminded each other that they both loved and needed one another despite the fact that they were going to colleges on opposite sides of the country.
In Season 6B, Scott (as well as the other main members of the McCall Pack, Lydia and Malia) have continued on with their lives while missing Stiles, who has been doing an internship with the FBI in Quantico, Virginia. Shortly after Stiles left, a creature known as the Anuk Ite, an ancient and powerful shapeshifter who was locked up by the Wild Hunt and was subsequently released when the pack brought Stiles and the other captives of the Ghost Riders back to Beacon Hills, arrived in town, causing Scott, Malia and Lydia to postpone their college plans; by doing so, they went against what Stiles wanted for them, which was for them to leave Beacon Hills and get on with their lives. Ever since this point, Scott has struggled with whether or not to bring Stiles back into the fold, acknowledging that they need his help (as well as the fact that he would be mad if he knew what they were trying to do without them) but not wanting to tear him away from an opportunity that Stiles has clearly been thrilled to be taking.
Scott and Stiles are also known as Sciles (and are less commonly known as Skittles or McStilinski) by fans
It is unknown when exactly Scott and Stiles met, but they have known each other at least since the third grade, judging by comments made by Sheriff Stilinski, Melissa McCall, and Scott and Stiles themselves. According to Scott, the small scar on his cheek is from when he and Stiles were playing lacrosse in the McCall House when they were kids, during which time Scott dove to catch a ball Stiles threw toward him, landed on the glass coffee table, and shattered it, cutting his face and forcing him to get three stitches. ("Insatiable") They also apparently used to skateboard in the tunnels under the water treatment plant until Sheriff Stilinski caught them and forbade them from going back, suggesting that Scott and Stiles have been troublemakers from a young age. ("Ouroboros")
Scott, however, was still suffering the side-effects of his own injuries caused by Theo prior to his brief death and subsequent resurrection, and it took him longer than expected to make it to the hospital. After being awoken by Jordan Parrish, who had just found a catatonic Lydia in the woods, Scott learned about Sheriff's condition and rushed to the hospital to both comfort Stiles and inform him about Lydia's similarly-precarious situation. Unfortunately, upon Scott's arrival, Stiles became furious and attacked Scott, shoving him against the wall before throwing him onto the ground and pinning him there while he demanded to know where Scott was when his father was being attacked, though he had already been informed by Theo that Scott was already in danger prior to giving him the Sheriff's location.
After Melissa and Dr. Geyer pulled the two apart, Scott pointed out that Sheriff Stilinski wasn't the only one who was hurt, and Stiles, assuming that Scott was talking about himself, scoffed and remarked that Scott would heal, not realizing that Scott was actually talking about Lydia. Once Stiles returned from his failed attempt to visit Lydia, where he was rebuffed by Natalie Martin, he rejoined Scott, Melissa, and Parrish in the morgue, though he made sure to keep his distance from his estranged best friend while they discussed the Sheriff and Lydia's current conditions and Theo's upcoming plans.
In the morgue, they determined that Theo was trying to locate the Nemeton in Lydia's mind to gain an advantage, and had the Sheriff attacked to ensure that no one would interfere with Liam's attempt to kill Scott. When Parrish insisted that they needed to find Theo, Melissa argued that it was too dangerous, since he almost killed Scott and tried to have the Sheriff killed as well. Stiles replied that Theo made it clear he didn't want the Sheriff to die, but Parrish was skeptical that they should believe him. Despite the numerous warnings, Stiles decided that he needed to talk to Theo, since he could have information on how to save his father, and only reluctantly allowed Scott to accompany him to do so due to the fact that Theo didn't know he had survived their fight.
The two then went to the McCall House, where Scott hid in the upstairs hallway and eavesdropped on Stiles' conversation with Theo in the foyer, during which time Theo revealed his Werewolf-WerecoyoteChimera nature and admitted to knowing what the Dread Doctors were planning and what creature Parrish was, though he was unwilling to share the information. After a tense ending that led to Theo shoving Stiles against the steps so hard that he briefly blacked out, Scott managed to rouse him, only for Stiles to slap away his proffered hand. They then discussed Stiles and Theo's conversation and determined that it wasn't Theo who attacked the Sheriff, but another Chimera.
Since he had the information he needed, Stiles set off to search for the newest Chimera on his own and firmly refused Scott's help, forcing Scott to step in front of Stiles' car to stop him long enough to convince him to let him accompany him on his search, arguing that he didn't have to do it alone and that his werewolf senses could allow him to find the clues he couldn't. Stiles once again brought up the fact that Scott trusted Theo, which lead Scott to remind Stiles that he, too, had trusted Theo near the end after Theo saved Stiles' life from Josh Diaz's attack.
When Stiles reminded him that he didn't even know the true story of what happened when he killed Donovan Donati, Scott insisted that he didn't need to know, because all that mattered was saving his dad. He then argued that the two of them (and the rest of the McCall Pack) had survived the Alpha Pack, a Dark Druid, and Deadpool assassins, which meant that they could survive the Dread Doctors and Chimeras as well, an argument that eventually caused Stiles to relent and allow Scott to accompany him.
After learning that the newest Chimera was a young teenager named Noah Patrick, Scott and Stiles drove to Beacon Hills High School, where they broke into his locker to get a lock on his scent. Scott then tossed the jacket he retrieved aside, where it was caught by Malia, whom he had called for additional help despite Stiles' insistence that they do it themselves, arguing that they needed all the help that they could get and that Malia already knew what Noah looked like as a result of their previous encounter.
Scott, Stiles, and Malia tracked Noah to the railway depot, where Malia informed Scott that she and Stiles had broken up, leading Scott to admit that he and Stiles seemed to have broken up as well. In the tunnels beneath the railway depot, they found Noah, who shoved Stiles so hard that he hit the wall and was briefly knocked out again, causing Malia to tackle Noah while Scott roused Stiles awake. This time, however, Stiles took Scott's hand and allowed him to help him up rather than swatting it away, indicating that there was still hope to mend their friendship.
When it became clear that the Dread Doctors had deemed Noah to be a failure and were coming after him to kill him, Scott insisted that Stiles help Noah to safety while he and Malia, along with help from Chris Argent, slowed the Doctors down. After managing to do so, Scott, Malia, and Chris returned to the hospital, where they were relieved to hear that Sheriff Stilinski had survived the attack and would recover.
Stiles gave Scott his Jeep as a goodbye present before the two left for their respective colleges, with Scott attending the University of California-Davis and Stiles attending George Washington University in Washington D.C.
Scott and Stiles have "passed the baton" (or, in this case, Stiles' aluminum baseball bat) to Liam and Mason, who are effectively filling their places in the McCall Pack while the former two are in college.
Both, Stiles and Scott have dated pack mate Malia Tate.
Though Stiles and Malia were only together in season 4 and 5A, Scott and Malia have been together for Season 6B and the time jump.