I was a living at my grandpas spare trailer about a week ago.(I was paying rent and bills) I told him give me a week I be out and that I wasn't going to pay rent so I can move out. He agreed and said okay. Well, since I moved they want to take me to court for 400 bucks for my bills and rent, after I already came to an agreement with him. My question is what can they do (get a way with me paying) to me in court if the bills aren't in my name(their in grandpas) and there is NO LEASE?

P.S. the people before me that lived in his trailer, didn't pay any bills or rent when they left, I paid them for him when I moved in,

Having a written lease or not changes nothing in this case...

They can try and sue you for it... and if they can show the bills were incurred while you were living there... they stand a good chance of winning. However its not a slam dunk..