Accidental Time Lord
The Archivist has a strange and storied origin. He was once both Nathan Ferguson and The Professor.
Nathan Ferguson inherited but one thing from his late father, an old fob-watch. What Nathan didn’t realize was that the watch contained the personality and physiology of an exiled Time Lord. When Nathan opened the watch, the old device detected trace amounts of the Professor’s DNA and attempted to rewrite Nathan’s own mind and body.
The result was that Nathan, with a body somewhere between a human and a time lord, was now in a constant state of conflict for his own soul with a power-hungry megalomaniac. In a moment of false triumph, the Professor took over and, hoping to regain his form and mind, forced a regeneration onto Nathan.
However, the result was something else entirely. No longer Nathan, no longer the Professor, the new entity chose for himself the title of the Archivist. The regeneration left the Archivist a full time lord, but many questions remain, the biggest one being: How many regenerations does this form have left, if any?
However, the Archivist doesn’t dwell on that. He instead prefers to enjoy the company of his friends and traveling on the ReTARDIS, taking a keepsake from every place visited in his own little museum he takes care of.