Warning: Major spoilers ahead for I Know What You Did Last Summer.
I Know What You Did Last Summer introduced a number of characters before starting to kill some of them off — here’s why Johnny was ultimately the first to die. The Amazon series has the same premise as the 1997 film of the same name: a group of teenagers run over someone following their high school graduation and dispose of the body to avoid being blamed for murder. A year later, the friends are stalked by someone who knows exactly what they did the summer before and the group at the scene become the primary target for revenge.
Johnny is perhaps the most empathetic of his friends, each of whom have their issues in I Know What You Did Last Summer. He’s also the only one who was friends with both of the twins, Allison and Lennon. Considering Lennon is the one who is killed on the night of the accident, with Allison pretending to be her dead sister without correcting anyone, Johnny is likely the first to die in a bid to get back at Allison. In some ways, Johnny’s death calls out Allison’s ruse, rattling her because he was the only friend she had and Lennon knew this.
Although Lennon is revealed to actually be dead, Johnny was on to the fact that something wasn’t right about the situation with his friend, still under the impression Allison was her twin sister. He caught “Lennon” smoking knowing full well that it was Allison who always had a pack of cigarettes on her. Shortly thereafter, Johnny was dead, gruesomely killed by the murderer, who dropped off his severed head at the location Lennon died, knowing Allison would drive by that very spot. It’s possible Johnny was getting too close to the truth and the killer couldn’t have him finding out Allison was still alive or risk ending their terrorization of her.
While the killer seems to want revenge on all of the friends who were in the car on that fateful night, Allison is the primary target and the person at the center of the vengeful acts. Johnny may have always been destined to die — this is a horror series, after all, and all of the friends will be targeted, if they’re not already — but being the first to do so suggests that the killer was aware that he was onto Lennon not really being Allison and would have revealed that sooner than expected in the grand scheme of things.
Johnny was also the friend who had the least closest relationship with Lennon, so it could be the killer was trying to make a point with his death being the first of all the friends in I Know What You Did Last Summer. Johnny’s death was horrible and is made all the worse because it was filmed to get to Allison and the others. If they weren’t taking the killer seriously before, Johnny’s murder surely did the trick. Which of Lennon’s friends will be the next to go in I Know What You Did Last Summer season 1 remains to be seen, but Johnny’s death will be haunting his friends for a long time to come.