A few days passed away, and Catherine, though not allowing herself to suspect her friend, could not help watching her closely. The result of her observations was not agreeable. Isabella seemed an altered creature. When she saw her, indeed, surrounded only by their immediate friends in Edgar's Buildings or Pulteney Street, her change of manners was so trifling that, had it gone no farther, it might have passed unnoticed. A something of languid indifference, or of that boasted absence of mind which Catherine had never heard of before, would occasionally come across her; but had nothing worse appeared, that might only have spread a new grace and inspired a warmer interest. But when Catherine saw her in public, admitting Captain Tilney's attentions as readily as they were offered, and allowing him almost an equal share with James in her notice and smiles, the alteration became too positive to be passed over. What could be meant by such unsteady conduct, what her friend could be at, was beyond her comprehension. Isabella could not be aware of the pain she was inflicting; but it was a degree of wilful thoughtlessness which Catherine could not but resent. James was the sufferer. She saw him grave and uneasy; and however careless of his present comfort the woman might be who had given him her heart, to her it was always an object. For poor Captain Tilney too she was greatly concerned. Though his looks did not please her, his name was a passport to her goodwill, and she thought with sincere compassion of his approaching disappointment; for, in spite of what she had believed herself to overhear in the pump-room, his behaviour was so incompatible with a knowledge of Isabella's engagement that she could not, upon reflection, imagine him aware of it. He might be jealous of her brother as a rival, but if more had seemed implied, the fault must have been in her misapprehension.
She wished, by a gentle remonstrance, to remind Isabella of her situation, and make her aware of this double unkindness; but for remonstrance, either opportunity or comprehension was always against her. If able to suggest a hint, Isabella could never understand it. In this distress, the intended departure of the Tilney family became her chief consolation; their journey into Gloucestershire was to take place within a few days, and Captain Tilney's removal would at least restore peace to every heart but his own. But Captain Tilney had at present no intention of removing; he was not to be of the party to Northanger; he was to continue at Bath.
When Catherine knew this, her resolution was directly made. She spoke to Henry Tilney on the subject, regretting his brother's evident partiality for Miss Thorpe, and entreating him to make known her prior engagement.