The Families

After fighting off the Lawrence vampires in Santa Carla, the Emerson family decide it would be best to take Hopper's niece to Hawkins to be reunited with him, after years of being driven apart by Jim's deadbeat brother. Unfortunately for Lucy Emerson and Jim Hopper, they weren't counting on El not wanting a new family member. They certainly weren't expecting the twice dead to follow them.
The Lost Boys 1987 x Stranger Things cross over
I had to fudge the time line a little. Not following cannon