I once, probably 4-6 years ago, used exports from Slack conversations to train a Markov Chain to recreate a user that was around a lot and then left for a while. I wrote the whole thing in python and wasn't overly well-versed in the statistics and math side but understood the principle. I made a bot and had it join the Slack instance that I administrate and it would interact if you tagged it or if you said things that person always responded to (hardcoded).

Well, the responses were pretty messed up and not accurate but we all got a good chuckle watching the bot sometimes actually sound like the person amidst a mass of random other things that person always said jumbled together :D