In a world where Derek trusted Uncle Peter enough to tell him about his hot, new and much older girlfriend, the Hale fire was averted when Peter reported Kate Argent to the newly promoted Sheriff Stilinski.
The Hales survived, but little eight-year-old Stiles and Noah couldn't do nothing against Claudia's fronto-temporal dementia. The Stilinskis were decimated, but the McCalls were there for them, as were the Hales (out of some kind of moral debt, apparently).
Stiles, being influenced by so many werewolves (even without knowing it), ends up discovering a part of him destined to remain hidden: he is a spark, by birth.
And not only did his magical core awaken, little dots of magic around Beacon Hills were appearing more and more frequently, without any explanation. Foreign creatures were drawn to the Beacon's awakening, and the Hale pack seemed to be outnumbered to stand against the invaders, even with the help of their druid (Alan Deaton), and his newest pupil (Stiles Stilinski).