Well you see, Madalyn is indubitably a very interesting character seing as she would never award sexual favors for free. After all she's a well seasoned witch, who brews potions..
The only chance Henry has to get her loving (and definetly not manly,
Harpocrates) arms wraped around him is her extensive interest in esoteric titapak treasure, and that's perhaps what she's holding in her hands, or at least what got him in her private washroom in the first place. Otherwise it's a love potion, it has to be.
They say you can't bullshit a bullshitter but can anybody out witch a witch? I can't see it. And while we're at it what the hell is Madalyn actually after? An artefact? Knowledge? Power? The same things as Sofia? We know that Sofia is in pursuit of the fabled Tikpac language, which, like the Enochian language of Angels discovered by the Elizabethan Magus Doctor John Dee and his Seer Edward Kelley, is purported to have world-changing supernatural power but so far Madalyn's agenda remains obscure. Is she seeking some magic to resurrect her brother (biological, fraternal or both) from semi-life as a shade into physical manifestation in the real world? Or is she seeking some occult means to achieve some other end peculiar to the Church of Cambian, e.g., a way to make incarnate a Saviour, or some other preternatural being, for purposes not made clear yet in the story?
It's stuff like this that makes Treasure of Nadia so fascinating and keeps us aficionados hooked.
Witchcraft and magic, especially of the darker variety, often includes various kinds of sex in worship, initiation, ritual and ceremony, so there is a real possibility that Madalyn is grooming the MC to play the male role, in some sex-magical event, in order to invoke/evoke some supernatural power or being or accomplish some other end at some point in the future. Madalyn is one of ToN's most beguiling and fascinating characters and I don't mind admitting publicly that I would be in there, oh yes, like a hot knife into butter, if she gave me the green light, be she a four century old, demonic, platinum-haired succubus or not. Even if she devoured me afterwards like a female mantis often does with her male after mating. What a spectacular and unusual way to go!

Even more fun and environmentally friendly than a Viking funeral or I'm a Dutchman!