Aurora
Aurora was a traveller on the celestial frontier in the second century AHE, and Cat's key character in Frontier stories, part of the Starlight Cycle. Aurora is a seer who has magical visions, which mostly depict the present but can also show the future. Little is known about her backstory, though she was old friends with Cathal Sior at some point in her past. Aurora and Cathal met back up at some point around either 84 or 175 AHE, depending on the source, and ran into Aerule Ceruleus and Isan Segba, with whom they started travelling.
Many sources give her name as "Aurora Álainn", which Kerry and Tom regarded as canonical. They tended to pronounce the surname as "al-AYN", though álainn is an Irish word (not surname) pronounced "AH-lin". There is no evidence that Cat ever used the surname "Álainn" for Aurora or was even aware that Kerry and Tom had introduced it. On one occasion, Cat called her character "Aurora Xavier", but this surname was not widely used by her; normally Cat just called her "Aurora" even where other characters were shown with surnames.