Once you find him, the only way to see where he is, will be for him to walk through a flare. Don't throw your flare down on top of the track he just left, throw it a little further out in front of where you think he is. When he walks through your flare he will become visible. You can take this opportunity to tame, or you can throw a Hunter's Mark on him - which will keep him visible to you when he goes back into stealth. Hunter's Mark will make him visible to you, but only you when he's in stealth.
(Tracks are now facing the correct direction. You no longer need to follow them backwards.)
Portent's Path starts on Autumnshade Ridge, just northeast of The Gate of the Setting Sun. He turns around there just in front of the elite quest npc Bai-Jin the Butcher. From there he winds his way through pretty much the entire zone heading in a mostly eastward direction until he reaches the wall just north of Mogu'Shan Palace. It takes him about 32 minutes to move from one end of the path to the other. When he reaches the end of his path, he simply turns around 180 degrees and heads back in the direction he came from.
|Click map to Enlarge|
|In the above screenshots Portent is heading toward the west end of his path, where he turns around 180 degrees in front of Bai-Jin the Butcher and begins walking back in the direction he came from.|
|Above from left to right: Portent is moving south through Autumnshade Ridge, then east by The Five Sisters. In the right screenshot he is heading northeast through Winterbough Glade.|
|Above from left to right: Portent is heading north through the Ruins of Guo-Lai, then turning east in front of Ruins Rise. In the right screenshot he is moving east across The Emperor's Approach.|
|Above from left to right: Portent is passing the Golden Pagoda, while moving south along The Emperor's Approach. In the right screenshot he is moving east through The Summer Fields.|
|In the above screenshots Portent is heading north through The Summer Fields parallel to Mogu'Shan Pallace.|
|In these last screenshots he is heading toward the eastern end of his path (just north of Mogu'Shan Pallace), and then turning around.|