which brothers fought over the theban throne
The right to the Theban throne is why Antigone's brothers fight. Eteocles and Polyneices are twins. So they both have rights to the throne that's vacated by their father and half-brother, Theban King Oedipus. The brothers are supposed to alternate years in a joint power sharing arrangement. Eteocles gets to occupy the throne first. But he refuses to give the throne up once his year his over.