When Spider-Man encountered the Lizard in front of the Connors house the two of them fought. Billy then came outside and witnessed the fight. Billy then called the creature daddy which distracted Spider-Man long enough for the Lizard to get away. As Margaret came outside Spider-Man asked her if he heard Billy correctly. She then told Spider-Man that the Lizard was Curt. After Spider-Man managed to cure Curt Connors he returned Curt returned home to Margaret and Billy.
In the comics
At one point Curt injected Billy with the lizard formula while he was under the influence of a mysterious meteorite that caused savage behavior. Both the Lizard and "Lizard Jr." were eventually captured and turned back into humans.
Sometime later Curt turned back into the Lizard and he killed and ate Billy.