Kathrine

Kathrine is one of Roofus' daughters. She can be found towards the end of Lower East Quack, near the cinema on a block of ice.

How to Rescue
To reach her, look up to the top of the cinema and shoot the water supply. It will fall down and the contents will freeze over a pathway to her.

In Viggo's Revenge, it is possible to save her without shooting the water supply. By getting on the subway up above in the Upper East Quack where Jonathan can be found (standing on the track railing does not result in an auto fluff), you can jump off of the tracks and onto the block of ice.