First thing. Zavala is known as an “Earth Born/Bound” Awoken. When Mara and her people left the Distributary, two factions arose. The Reefborn and the Earthborn. The Reefborn, led by Mara, wanted to bide their time and create an established society within the system before going to Earth and helping out over there. The Earthborn though, wanted to head straight to Earth and help Humanity. It can be assumed that Zavala was one of these Earthborn Awoken, as he was in a relatively nice ship with a ton of other skeletons. They could have possibly died upon reentry into Earths Atmosphere. This means that we can trace Zavalas Origin all the Way back to the collapse with little discrepancies in the timeline, nor gaps and lapses where he could have been something “more”. Second Thing The Witness is trying to make a new Disciple. He has been attempting this since Beyond Light, but it has become especially apparent within this Campaign. We don’t know as of yet why he needs a light bearer Disciple, especially since he is already so close to finalizing his plans to Carve the universe into what he wants. With that being said, here is what I speculate [spoiler]The Witness lacks a pure connection to the Traveler. The same reason he needed the Ghost to connect the Veil and the Traveler by highjacking the Ghosts own connection, the Witness plans on using a Guardian, and a willing one at that, to turn the Travelers light upon itself, and thus, get full access of it. This will ultimately allow him to completely carve the Universe. Of course this is theory, and boarder-line baseless, so take it with a grain of salt. [/spoiler]

[spoiler]The Witness is tempting everyone, we see Crow and Cayde given similar visions while we hear the Witness tempting us within the ViDoc. Zavala is simply the character most susceptible to temptation with his past, being that he had the old wound of his dead wife and son reopened just over a year ago. He got over the grief of causing the death of his son, but it’s clear he very much misses his wife. Zavala has also been mentally beaten down over the course of Destiny 2’s releases, from having his faith in himself and the Traveler shaken repeatedly, losing multiple friends and seeing our efforts to combat the Witness ultimately prove fruitless.[/spoiler]

He wants the traveler to reshape Lubrae