Charlie Bowman is the son of Will Bowman and Katie Bowman. He has been separated from his family since The Arrival with no contact. By the time of the events described in most of Season 1, his family have had no idea where he is for nearly a year.
It's not until the Season 1 finale, "Gateway" that we get confirmation he is alive.
In season 2 Charlie is shown to be in a gang of street urchins who work for a gang lord named Soloman. His father eventually finds him but discovers scaring on his ankle because of abuse he has suffered from Soloman. His father kills Soloman and the adult members of his gang in retribution.