My knowledge of 1.0 is admittedly secondhand, but as far as I understand it there is no clear answer on what might have happened to your path companion. Like the WoL's backstory, the exact nature of one's Path companion is left rather vague, especially considering their race, class, and personality were chosen by the player. Nobody is quite sure what might have happened to them after you parted ways with them. Many assume that they died in the Calamity or on the plains of Cartenau. They aren't even mentioned at all in the lorebook, so it's possible the path companion was completely retconned. Alternatively, they might have been one of the nameless scion adventurers hanging around the Waking Sands. Either way the memory melting antics of the Calamity would make it so they wouldn't have recognized the 1.0 player character if they saw them, at least for a while. As far as them coming back, between their player defined nature, their lack of mention in other materials, and their lack of major plot importance, I don't really see them reappearing.