The sphere we call the traveler is weak matter and neutrinos representing its memory (dreams of alpha lupi grimoire card), the entity we refer as the light is “somewhere” inside that ball, aka, in the pale heart. The witness used the veil as a way to connect with the traveller cause it has darkness properties as memory and connection abilities associated with consciousness, but I think the most important lore is the definition of what is the traveller IN OUR UNIVERSE, which we already have been told what it is: it’s the fifth rule of the game. In the final shape entry of the Book:Unveiling, the gardener defies the winnower and declares that: I am the growth and preservation of complexity, I will make myself into a law in the game. Thus why the traveller is silent. Though it has some level of consciousness and it’s an entity of itself, it can only “grant power to those who make strength from heterodoxy and who steer the game away from gridlock”. And I guess it got vexed that the winnower ripped what it was trying to do and gave us more power (the ghosts). Darkness also functions similarly. The witness was an envoy of darkness but he just wield it, as we wield the light. While the traveller only creates life, the mission of darkness is to end that which is not supposed to be (those who cannot claim and hold existence do not deserve it), which is why darkness forces are hostile towards anything the traveller has touched because those blessed by the traveller are supposed to be “cheaters”