Triplex Deal - Need advice/feedback

[David Towery]

I'm currently about to go under contract on a fully occupied tri-plex outside of Houston, TX. The numbers seem to work ok for me. What scares me is that the owner has just put in a new tenant that does contract work. The current owner came to an agreement that the tenant would not have to put down a deposit if the tenant would fix/replace the toilet and paint the inside of the unit. The tenant moved out of his efficiency unit elsewhere and into this unit because him and his girlfriend got back together and now she wants to move in with him and they needed some more space. Seems like a volatile situation with what seems to be inconsistent pay, a move in girlfriend, and no deposit. He did come recommended by one of the current tenants in the tri-plex I'm purchasing. 

I just wanted to get any thoughts/advice/concerns from people who may be a little more experienced than me (I own a duplex and have been a landlord for all of 3 months now so that's probably everyone on this forum). Would this be a deal breaker for anyone? What can I do to protect myself? 

Appreciate any input.

David