Jeremiah isn't actually a member of Jon's Spirit Team. He is instead a Guide that is with Jon all the time. His name was mistakenly spoken of as being Joe, or Joseph.
Jeremiah was a farm hand before taking the King's Oath. He had lived within the South of England. He spoke with a heavy accent and used words that are now unfamiliar and unlike Jon's current language. He fought against the French in defence of the Realms. To the best of his memory he passed in 1736.
