After escaping through a portal in Uatu the Watcher's citadel back in Quasar #6, the Living Laser has been trying to find his way home through alternate realities. Unfortunately, each attempt splits off another Living Laser who pollutes the timestream. Someone has to clean this up and Uatu picks Quasar for the job.
Quasar travels to realities from:
What If? Vol 1 #32 (Earth-82432) "What If The Avengers Had Become the Pawns of Korvac?"
What If? Vol 2 #1 (Earth-89721) "What If the Avengers Had Lost The Evolutionary War?"
What If? Vol 2 #14 (Earth-906) "What If Captain Marvel Had Not Died?"
What If? Vol 2 #24 (Earth-9140) "What If Wolverine Had Become the Lord of Vampires?"
What If? Vol 2 #32 (Earth-9112) "What If Phoenix Had Lived?"
What If? Vol 2 #4 (Earth-1089) "What If the Alien Costume Had Possessed Spider-Man?"
What If? Vol 2 #25 (Earth-9151) "What If Set Had Come to Earth?"