Volunteer

The Volunteer is the character you play as in Desolate. Apparently signing on with them in order to restore the world to what it once was. He is just one of possibly many volunteers sent to the island in order to combat the horrors of the land. He believes in New Light's mission of keeping the horrors of the island at bay and contained, and thus he finds himself on the island in order to fight back against the horrors.

Spoilers: Overtime he uncovers the truth of the island, and sets out to ensure the truth gets out and those that are responsible are punished.