Looking how old Dennis looks in the last image (number 6), must have passed quite the time... Considering he is a Dhampir (a half-blood vampire), and considering he might age ten times slower than a person. Maybe not... The point is, the poor soul under Mavis' "care" isn't Johnny... And Mavis truly lost it.
Now, another question... Is this the first time? Or how many times has this cycle repeated?