I'm currently reading Morgan Llywelyn's historical novels about Ireland, beginning with Lion of Ireland, which chronicles the life of Brian Boru, and continuing with Pride of Lions which tells of the lives of his surviving sons and daughters after the battle of Clontarf in 1014. And what I'm coming to realize is that while they're outwardly about Brian Boru's lifelong quest to unite Ireland and his son Donough's efforts to hold it together, they're almost as much about Gormlaith of Leinster's lifelong efforts to tear it apart in the quest of her own personal aggrandizement and vanity.
On balance, Ireland would likely have been significantly better off for much of the last thousand years had someone slit that woman's throat before she was first married, or at the very least before she got her hooks into Malachi Mor. She was personally responsible for starting at least two wars, if not more, including the one that was settled at Clontarf. Not for nothing was she the most hated woman in Ireland.
I always wonder