Try 'The Faithful Tribe' by Ruth Dudley Edwards for an insight into Orangism in Northern Ireland. Anything by Robert Kee, Tim Pat Coogan or Conor Cruise O'Brien (as with everything in Northern Ireland, keep a critical eye open for inherent bias). To get any sort of perspective on NI, some history is important. Biogs of Collins, DeValera, Cromwell, Robert Emmett, Countess Markiewicz etc will help.
Tim from Bit on the Side