I remember that Kayla was called to one of the hospital rooms for some emergency, that is where she got gassed, and I believe it was Steve who found her, thus he, too, quarantined. Benji came to see him then.
Kayla had taken Steve away to to some isolated place, an island or something, where she worked on him regaining his memory. This was all off screen, they returned and he had remembered. We saw none of that.
After Steve & Kayla were unable to adopt Pocket, she got pregnant with Joey. I remember there was some sort of black mark on his wrist or thumb (which was supposed to indicate a Stefano thing of some kind, but the writers wisely chose to just forget/change/ignore/ never to be spoken of again.
@JasonD...yes, of course I meant Stephanie. LOL.