I am renting a house owned by my dad. My fiance my brother and i agreed to pay a 1/3 of everything. My brother left with the clothes on his back. All other belongings are still in the unit. My LL tells me 2 weeks before rent is due that i will have to cover his share, even though he isn't physically there all of his stuff is still there. Is that legal? What do I do?
Yes. It it 100% legal. Your agreement to split rent in thirds is between you, your brother and fiance only. It has nothing to do with the LL and isn't legally obligated to honor the personal arrangements and agreements between yourself and the other renters. If rent is $1000, then the LL is legally owed $1000 no matter who is living in the apartment or who has moved out.
You pay the rent in full and get your brother's portion of the rent for this month either by asking him for it or taking him to court.