UESP
Felisa Ulessen, a Dark Elf mage, is the Mouth for Mistress Therana. She can be found in the Telvanni Council House in Sadrith Mora and is a quest giver for House Telvanni.
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Galos Mathendis implies that Felisa may be somewhat mad herself.1
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Oh, hello, %PCName. You’ll have to excuse the clutter from my projects. But at least I don’t have kwama eggs decorating the walls, eh? Ha ha! Speaking of Therana, I do believe that serving as the Mouth for a clearly and hopelessly mad mistress was starting to affect Felisa Ulessen by the time I retired. You know I caught her keeping a pet spider in her robe? She ate it when I pointed it out…
— Galos Mathendis (dialogue)1