As I understand it, if Christine from
this example had instead changed her name from Christopher to Alexandra, and went by the shortening Ally, then she could still be vassalized by Chris but not Ally. If Ally then said “I'm Christian”, while thinking about her believe in the divinity of Jesus, any fairy who heard just the first two syllables of this sentence would become her master even though she wasn't thinking of anything related to her name at all. Is this right? Would fairies who heard the full sentence and knew Christian was a mortal name become her masters if they didn't try variations like “Chris”?
How does the clicking-into-place of names work? It seems like it would be too powerful, so I think I misunderstand it somewhere. It seems like Promise could be vassalized by any fairy considering her name might be shortenable to Al, Ali, Alys, Alisyr, Alisyrra, Lys, Lisyr, Lisyrra, Syr, Syrra, Syrrabel, Rabel, Bel, or various other possibilities. Depending on how precise the names need to be, Syr might work for Arcane too. As fairy names are often (always?) several syllables long and relatively pronounceable, it seems like it shouldn't be too hard to guess syllables and be right fairly soon, and the clicking-into-place would mean it could be done without alerting the target to what you were trying.
How do name-based nicknames that aren't strict shortenings work? If
William, a modern English-speaking American, introduces himself as “Bill”, does that count for vassalization? What about if
Williame, the famous 11th-century duke of Normandy and king of England, who popularized the use of the name William in English, introduced himself the same way despite this abbreviation not being common yet? Would these answers change if instead they introduced themselves as Billy or Willy? If the ship
Jehovah had been enough of a person to be vassalized (I assume it isn't, but being electronic is not a problem, and both Jane and Jarvis could be vassalized), could it have been vassalized with Jovah or Yovah? How would this list for any given person compare to what Elspeth could truth-voice refer to that person as (as seen in the fifth paragraph of Radiance, where she called Golden “Izzy”)?
What about name translation? If a modern American named William were to introduce himself as Guillaume while speaking French, would this count? What about names with meanings in the language of native speakers; for example, if a fairy tried guessing that Fleur Delacour's name was “Flower”? Is the answer to that different if most people in the culture have meaningful names, as in MLP:FiM? How does this interact with fairy plainspeaking?
If the examples from both previous paragraphs would work, can they stack? Could Sharles, father of Shell Bell, be vassalized with a translation of the word “Shark”, or an American Anglophone named Richard with a translation of the slang word “Dick”?
Finally, how does this interact with forking and merging? Would both Sue and Admiral War have the same not-revealed-in-canon name their birth father had given them, or would one of them be unnamed (or, more likely, named whatever Admiral War had chosen when naming the different forks)? Is that somehow different than the answer for Shell and Bell or Timer and Nathan? What about the version of Juliet with memories of Soph, from before the merge? Would the merged versions of any of these be different? What about the
mnemic displacement and mnemic overload victims, pre-Downside-Belling?
While writing this I came up with two other questions (about Beast, with his name stolen from him; Soph, who was called The Key well before everybody remembers Soph being born; and about Mark, who was called by his original's name while growing up), but those are more about the specific enchantment, the specific spell, and Ser Galen's state of mind, respectively, than they are about fairy magic.
