Kleiver is a Wastelander, and appears as a support character in Jak 3. He also appears in Jak X as an opposing racer. His main role throughout Jak 3 is to assign Jak missions, and sometimes to act as an ally. He occasionally offers guidance to Jak - both friendly and unfriendly - and allows Jak access to some of his vehicles.
Kleiver has a very outspoken dislike for Daxter, and is easily agitated by him. He would not mind eating him, however.