Quote 4
"He is gone," murmured Sibyl sadly. "I wish you had seen him."
"I wish I had, for as sure as there is a God in heaven, if he ever does you any wrong, I shall kill him."
She looked at him in horror. He repeated his words. They cut the air like a dagger. (5.27-28)
Jim's ethical code is certainly more strict than those of the other characters we know – he believes in protecting his loved ones, regardless of whether the law deems it right or wrong.
Quote 5
As for Sibyl, I do not know at present whether her attachment is serious or not. But there is no doubt that the young man in question is a perfect gentleman. He is always most polite to me. Besides, he has the appearance of being rich, and the flowers he sends are lovely […] He has not yet revealed his real name. I think it is quite romantic of him. He is probably a member of the aristocracy […] I trust he is one of the aristocracy. He has all the appearance of it, I must say. It might be a most brilliant marriage for Sibyl. They would make a charming couple. His good looks are really quite remarkable; everybody notices them." (5.13)
Again, we see that Mrs. Vane simply relies upon appearance (like so many of the characters we meet here) as truth. Not wise!