Type MARVIN very fast. The game will say "marvin mode activated"
Press the ` button to bring up the in-game console.
Input command "spawn sh"(Without the quotation marks).
An in-game helper will appear. Talk to him and you are provided with options to increase faction reputation and spawn items. Also allows you to move forward in the main quests, all in the form of standard dialogue options.
To turn off marvin mode, type MARVIN very fast again.
Game will say "marvin mode deactivated"
When you're done with the Helper, you can kill him to get rid of him. :)