It's from a video game. Guardians have "Ghosts" who revive them when they die in battle. As long as you have a Ghost, you're more or less immortal. If your Ghost is killed, you can be killed. The Ghost is always with you, talks to you, and you have a relationship. It is a device in the game that tells you what you're supposed to be doing and it is directly linked to the plot of the game as well. The ghost has "light" a special, intelligent life force.
It's interesting to think of something with light, a life force that is helpful to humanity, as one's soul mate, instead of depending on another human to play that role. In non-fantasy/video game terms, it is almost like saying your soul is your soulmate, not another person. Or perhaps, the electricity that keeps you alive is your soulmate. It's human nature to crave relationships, but I appreciate the independence of this concept. Of course, this light would have a personality similar to/compatible with your own because you're basically attached to each other.
