Reilly always had a fascination with John the Priest, so I think it's supposed to be the Devil's manipulation. They did briefly really lean into that background after Kristen figured out the password to Stefano's computer (than Tony went blind retrieving). John the Priest was supposed to make him sexier for Kristen since she was guilt-trapped into being with Tony, which was actually pretty good thinking to have it reestablished for Possession.
I don't mind they brought Wayne back. John's missing past had so much potential, but it unfortunately became a prop for every head writer to use in another story.
I started watching Days in the summer of 1993. Every story from then until Possession was absolutely on fire.
I could swear I remember Laura's Carly using her training to sneak into the hospital and examine the records re: the monkey virus in 2006(?). I think that's the last time I remember her referencing it though.
It is always annoying to me when writers forget the initial specialization of characters. For example, Lucy Coe became so silly and dumb, but started out as a university law librarian. At the very least she should have known that Ian Thorndike was cribbing the works of Irish poets. Similarly, Carly went through the nursing training at GH as a physical therapist, but you'd never know it when she is either in an emergency medical situation or creating a spa for her hotels.