Merissa the Sea Witch

A sorceress from the Middle Ages, she was born somewhere in the British Isles (she herself doesn't know exactly where) to a witch who was murdered by monks when she was a small child.

She was adopted by the Church but she never fit in, often escaping from the island monastery and attempting to swim out to sea.

She's very sneaky and cunning, an excellent liar. She reminds me a bit of Lyra Belacqua.

She later discovered her latent magical powers and turned all the monks into monsters that helped murder her mother and other witches and innocents and converted most of the nuns to the power of the craft. All the rest of the clerics ran away in fear.

The monastery became her own castle in the sea. Many paladins attempted to reclaim it in the name of God, but they all failed, their bodies crashing into the rocks and the waves taking them away.

Eventually she perished but she was resurrected in the modern day to become a dark senshi for some unknown force. She went along with it begrudgingly, but she will later betray the force when it tries to impel her to do acts of true evil.

She's very confident, brash, fickle, and a bit selfish, though she treats those she cares about very well.