3 weeks ago I bought a car from a private seller from Facebook Marketplace. The transaction went okay and was handed over a signed title. Took it to get registered in my name and gave them the title the same day. This week I got a letter from the main DMV office saying the dude I bought the car from never registered it under his name and I needed him to do that so I could get the title in my name.

I messaged him about it and he wanted my me to sell the car back. I told him I already spent a lot of money on upgrades and wasn't going to do that. He then said to gift the car back. Thinking I had misread the text, I ask him if he meant to give it back to him for free. He literally said "yes".  I know he is not going to do what he needs to do to get worked out. I'm going to call TN Dept of Revenue on Monday to see if there is anyway around.

I'm guessing I'll need to get some sort of lawyer involved. What type do I need?

Go to Mississippi and get a Bonded Title. A friend of mine bought a Harley and the title was bogus, he lived in Tennessee but couldn't get the bike registered. He drove to Hernando Mississippi and got it registered. I don't know the exact procedure.

https://blog.suretysolutions.com/suretynews/mississippi-bonded-title-how-to-get-one

I was able to get it registered,etc I just won't be able to get the title in my name?

So was it an open title?  If so then go back later and tell them you bought it from the person on the title.  I've completed many title transfers that way.  Just don't even bring up the last party that had it.

The title was in his name but he never registered it, so they will not allow you to title it but will let you register it?

This makes no sense.