She’s being linked to Neal’s fairytale backstory (possibly)
Ausiello: Help me solve this latest fairy tale riddle: The show is casting the role of Katerina, a regal beauty in her 40s who possesses elegance, poise and purity of spirit. Thoughts? Theories? Bueller? No? Let’s see what TVLine’s resident OUAT expert Mitovich has dug up: “There is a Princess Katerina who is the Russian version of ‘Sleeping Beauty’ — which I suppose makes sense if Emma & Co. need yet another survivor of a sleeping spell to venture into the netherworld. But if the name is a foiler, this character almost reads like a ‘Glenda the Good Witch’-esque counterpart to Regina, and maybe she figures into someone’s fairytale land backstory.”
http://tvline.com/2012/11/27/once-upon-a-time-spoilers-community-true-blood-ask-ausiello/