Okay, sorry for posting so late. I didn't get a chance last night, what with the boards down. I just read the IC thread, so if my posts (particularly regarding buff spells) are too late, I understand.
Serpenteye, the answers to your questions. I'm sorry I took so long. I'm posting here so I don't disrupt IC actions.
1: Has Narcelia's mind been tampered with, prior to this intrusion?
Not to her knowledge.
2: Does Narceila recall (consciously or sub-consciously) how she survived after her fall into the river?
She dreamt she was captured by Illithids. If it was not a dream, perhaps they found her and took her somehow.
3: Does Narceila have any ambition to usurp the rule of the House?
No. She's content to let "nature" take its course, be it old age (ha!) or a knife in the back (double ha).
4: Is Narceila conspiring with any individual or group, for any purpose?
No.
5: Is Narceila loyal to the Spider Queen?
Yes, but her loyalties are weakened from the Silence.
6: Does Narceila love her mother, Ki'Willis Millithor?
Of course not.
7: Does she respect her mother?
Perhaps less so since her change, but definitely yes.
8: What are her feelings about Illithids?
She loathes and fears them, for being inferior beings who are hard to deal with (i.e., they aren't really inferior).
9: Has Narceila's body been tampered with?
Not to her knowledge.
10: Does she trust her mother?
As much as one drow can trust another. More than she trusts anyone except herself.
11: Who does she hate, fear, loathe, admire?
This is kind of vague, and it delves into things I haven't considered for this character. If you want more detail, or had a different spin than I answer, tell me. Since Narcelia's
dominated, she'll answer.

She fears Lolth and Kiaransalee, and Illithids to a very much weaker extent. She hates and loathes all non-drow. She hates and loathes drow who are not devotees of Lolth, and/or who are not in the House. She admires (distantly) the Matrons who managed to keep control of their Houses and retain all of their power or gain more during the Silence. Included in this group is the Matron, but that's a different sort of relationship, so "admiration" might not be the right term.
12: Has she ever broken the law of the Spider Queen?
Of course not!
13: Has she ever been disloyal to the House?
Of course not!
14: What exactly has she been dreaming the last week?
Take from the dream posts what you will. She wouldn't remember them precisely, or necessarily accurately, so use your experience in dreams and take what you will from them. The Illithid dream would be the strongest, since it was real (or so I'm assuming).
If Ki'Willis discovers answers different than those I've posted, let me know if she tells Narcelia in any way about that. The answers I've given are those that I, the player, know, and that Narcelia "knows." If Narcelia were to discover that she had been doing things she was not consciously aware of, it would change her greatly.