Here is my input from the "A Deal is a Deal" perspective......
You lent some guy money. You were smart to get the deed to his house. He was supposed to pay you back. He hasn't. He should've borrowed money from his mom, dad, gramma, brother, etc. so he could pay you back like he promised. He hasn't. What you need to do now is stop being personal about this and take the Donald Trump attitude of - "it's just business". Write the loser a letter explaining that you want to be paid in full within 30 days. Explain in the letter that this deadline is not negotiable and you will not accept partial, incremental payments. You want to be paid in full. If he does not pay you in full, then on day 31 you go and record the deed in your name and pay the fees involved. You'll want to call a title company first and order a preliminary title search ( less than $100 ) to see if there are any other mortgages, back taxes, current taxes and/or judgments or liens on the property. You'll need to know the total owed on the property. Then you'll want to talk to the predominant realtor in that area to get an idea of the home's market value. I've never heard of a 12 month period of ontime payments related to the previous owner of a property as a condition for financing. The home is in your name and the mortgage is in someone elses name and on someone elses credit. The payment history of the previous owner has nothing to do with you. You want to refinance. Call some mortgage brokers. Talk to a lawyer about the notice requirement and eviction process to get that guy out of that house. If he trashes the house out of spite, have the police come to document the intentional vandalism and arrest him for criminal mischief. You'll want to tell him in a letter along the way here that that's what you will do if he damages the property and that he'll go to jail and have to get a lawyer and miss work, etc. After you get him out, you paint the whole inside and outside of the house and throw it on the market for sale. Hopefully the house will sell for more than what you are owed and you will make a profit for your time and money invested.
All of this is assuming that the house is worth more than what is owed on it plus your loan to the guy.
If the house is worth less than what is owed plus what you have in it, you may just have to chalk this up as a learning experience. Or you could take him to small claims court and get a judgment against him for what he owes you and if he sells the house you'll eventually get paid.