Siobhan and Liam

Siobhan and Liam are both founding members of the Irish Coven.

Siobhan
Siobhan's beauty and impressive strength and combat skills that scared away so many men in her village attracted the attention of Sancar, a vampire who was building a harem, and chose Siobhan as one of his women. Before her newborn year ended, she killed him and then went on her own. Knowing she could not go back home, she explored the world of vampires.

Liam
Liam was a warrior of the Irish army. During one of the battles, his troop was attacked by a nomadic vampire who was using the war as a disguise to feed. Liam was the last to be bitten, but because the vampire was already satiated, he did not finish him off and Liam was left on his own.

History
They first met when Liam was still a newborn and Siobhan took him under her wing and taught him everything that she'd learned about being a vampires, the advantages and the laws. Over time, the two bonded as a couple, and then they added Maggie into their coven.

Breaking Dawn
Siobhan and Liam, and Maggie, travel to Forks and agree to help the Cullens testify against the Volturi's accusations.

During the confrontation, they stand next to each other as Siobhan converses with Aro about Renesmee Cullen's human and vampire traits. After the situation ended peacefully, Liam and Siobhan return to Ireland with Maggie.