Guyven of the Road is a Halfling explorer in the Original Campaign.
Guyven will show up automatically at Crossroad Keep if you found him all three times in Act II. You will find him first on a ledge just before the Bonegnasher Caves. The second time you will rescue him along the Approach to the Githyanki Caves (to rescue Shandra Jerro). Finally Guyven appears beyond one of the houses in the desolated Ember (after it's been destroyed, while you're looking for clues for your trial).
When you meet him at Ember, you must tell him that he'll always have a place at your fire in order for him to appear in a room just off of the main hall in the Keep.
Speaking to Guyven in the Keep activates instances where you gain a small amount of experience for visiting four places he has not seen (such as the Strange Clearing and Ammon Jerro's Haven). Guyven himself doesn't do anything, but you can get a "Pathfinder" history feat by telling him of these several unique places (there will be a message when you've found a place you can tell him about).
After two stories told to him, Guyven will alert you to an item hidden outside the keep near the graveyard.
Guyven disappears from the keep when you begin your assault on the Shadow forces and when Lord Nasher occupies the room after his forces are defeated at Highcliff, just before your assault on the bridges late in Act III.