It depends on what the fugitive is wanted for. When you harbor a fugitive, you become an accessory after the fact. In many jurisdictions, including Massachusetts, an accessory to a crime is just as guilty as the principles of the crime. Thus, if the fugitive is guilty of murder, you could face the same punishment. If the minor is a federal fugitive, you can be found guilty as an accessory and/or you can be found guilty for the separate crime of harboring a fugitive (18 USC 1071). The latter of which faces punishment of a fine and/or up to five years in prison. Said it all.