Portent - Trackable Hunter Pet (Quilen)

Portent is a level 90 Quilen that can be found patrolling through the Vale of Eternal Blossoms. He is one of the rare elite trackable hunter pets introduced in Mists of Pandaria. He is an exotic beast, therefore he can only be tamed by hunters that are specced Beast Mastery. Like Madexx, the scorpion in Uldum, he can spawn in several different colors. In Portent's case, he spawns in four: blue, red, purple and green. I believe each color is unique, and the color he spawns in is totally random. 

How to track: Like the other trackable hunter pets, you will not be able to see him when he's up. He is completely stealthed. In order to locate him, you will need to find and follow his tracks - tracks that thankfully only hunters can see. Once you've found his tracks you'll need to follow them until you don't see any more. This is where I like to wait and watch where I think that he'll be walking next. Often times you'll see a new track appear right in front of you - this means you've found him!

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.

Portent's tracks are called "Dusty Tracks." Like other beasts' tracks they do not stay up indefinitely; the furthest ones behind disappear one by one as new tracks are created. His tracks are dark brown in color and almost his entire path is on bright yellow ground, making his tracks one of the easier sets to find. Although they do stand out well, I still recommend turning the ground clutter option down to low to make finding them a little easier.

(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

Below are some visuals of Portent moving through his path; starting from the west end of his path in Autumnshade Ridge moving east toward Mogu'Shan Palace.

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. 

I've got a video below that shows Portent's full path, following him from the west side of the zone moving east. The video has been sped up x3.

In this second video below, myself and a couple of other hunters watched him walk a short ways until I finally tamed him.