Matt was just "a kid around the block" who hung around Kira's cott (makeshift dwelling), which was not far from the edge of the forest. Matt lived there, along with other Fen people (forest dwellers), who were considered primitive and below the status of the village dwellers.
At the beginning of the story Matt comes to Kira's aid by salvaging several things from her previous cott just before it was to be burnt to the ground. As Kira's mother had died of an unknown illness, the community members feared contamination. Furthermore, it seems as if burning was a ritual of purification of some sort to help avoid the spreading of disease and an eventual epidemic.
Later on, Matt uses his knowledge of the forest to help Kira find her longlost father, whom she presumed to be dead. As the communities scattered about are isolated and estranged from one another and that even the forest itself is hostile to trespassers, Matt must defeat "the powers that be" in a very self-sacrificial way.