Lucretinaus' son, Cassius Olcinius, is under a spell of invisibility because he has failed to pay his debts.
"My son is what??? That explains why I haven't seen him for days. He's a good boy, just a bit out of touch with things. I really appreciate you helping him out here. I'd do it myself, but I really can't take the time to leave the store. Here, take this to help you along."
(After paying Cassius' debt) "I see that you paid the debt my son owed. I thank you for your help. Here is a reward for all your efforts."
(If the Nerevarine has already paid Cassius' debt before speaking to him) "You've paid the wizard my son's debt? I thank you. This should cover the money he owed, and a little something for you as well. Your efforts are appreciated."
debt to pay:
"Cassius did what??? What??? Oh, that foolish boy. Still, he's mine, and I do love him. Here, take this money and repay his debt for me. It amazes me what young people will do sometimes."
(If the Nerevarine has already paid Cassius' debt before speaking to him) "A debt to that wizard? Foolish boy. The number of times I've heard about stupid things Cassius Olcinius has done would turn your head."
Fevyn Ralen: "Fevyn isn't a bad sort, for one of those wizards. From what I hear, he does an excellent job, but his prices can be rather steep."