Patrick the Celt is a character who can be encountered in Fallout from time to time while traveling. He's the descendant of an Americanized Celtic family who has a strong vibe to keep his "ethnic heritage" alive. To do so he maintains lineages of Celtic music, food, clothing -- you name it. Never mind that who knows if the British Isles still exist at all... among other things, he's a storyteller and a collector of history. While telling tales of the rest of the world was really outside the scope of the game (and it would've been really boring for the player to wade through pages of history-through-a-Celtic-lens), his expertise meant that he could rub off a little on the character in matters of jokes, tale-telling and singing -- the sorts of things that help with Charisma.