You had been bit by the Alpha, at the time this was Peter Hale. You were seriously injured as the bite was fairly powerful. Stiles had found you on the football field with blood everywhere.

He took you to the hospital, you were in a coma for a couple of days and Stiles was by your side the whole time, waiting for you to wake up. Eventually you woke up but you seemed tired . "Hey.. do you remember what happened?.. I also got you some chocolate." *Stiles said as he gently handed you the bar.