alt Hacker NewsGood point, informal letters might actually be a better source - AI chat is (usually) a written rather than spoken interaction after all! And we do have a lot transcribed collections of letters to train on, although they’re mostly from people who were famous or became famous, which certainly introduces some bias.
The question then would be whether to train it to respond to short prompts with longer correspondence style "letters" or to leave it up to the user to write a proper letter as a prompt. Now that would be amusing
Dear Hon. Historical LLM
I hope this letter finds you well. It is with no small urgency that I write to you seeking assistance, believing such an erudite and learned fellow as yourself should be the best one to furnish me with an answer to such a vexing question as this which I now pose to you. Pray tell, what is the capital of France?