Walt's dog was the first to find and wake Jack after the crash.
Vincent was also the reason Michael tried to bond with his son by going into the jungle to find the lost dog.
Vincent was the one character that no one suspected of doing anything wrong.
But one clue that everyone missed first time around was this:
if Walt was so attached to Vincent, why did he not bring the dog with him on the raft?
If the one true rule of the island was that the smoke monster could not leave it - - - that could lead to an assumption that Vincent was NOT real, but a smoke monster in disguise. Which makes perfect sense if the smoke monster wanted to learn about the new humans on its island. What better way to gather intelligence than roaming through the camp listening to what everyone was saying. Vincent would have been the perfect spy.
We were introduced to Vincent in an odd way. Shortly after the crash. Vincent was searching the jungle. While doing this, he heard a whistle. It was Christian, who we would know later, was dead. And this Christian form was actually a smoke monster. He called Vincent over and told him to go wake up "his son." As Vincent ran off towards Jack to do this, Christian stated that Jack "had work to do." Vincent then continued running until he found Jack, who had just regained consciousness. As Jack awoke, he saw Vincent running towards him through the jungle and stopping to look at Jack. Vincent then continued exploring the jungle.
But since he had a "light" coat, perhaps Vincent was a manifestation of Jacob, who some believe was also a smoke monster due to his immortality and his inability to kill another smoke monster, MIB. Perhaps, both smoke monsters needed to awake, reincarnate or "save" a dead or dying Jack in order to fulfill their mutual desire to "die and leave the island."
We know that many "lost" souls remain trapped on the island (the whispers) including Michael. In the end, Vincent returns to the bamboo jungle to curl up next to dying Jack. Was this Jacob comforting Jack for taking the leadership role on the island - - - to direct his soul to the afterlife reunion?
Likewise, was Jacob in Vincent form attached Jack's dying soul from the plane crash into the island realm so it could be prepared for the after life?
