The power of tenses in Brookner. This is worth some study. I've previously considered the apparently muddled time scheme of Look at Me (see here), and something similar is at work in Undue Influence. Take the following, also from chapter 8:
She found it safer to treat me as the joker I had become, but she is concerned for me, as if she knew that I was in danger, that I deliberately, from time to time, courted danger.Precisely when is the narrator writing? Long after the event, or at the time? That present tense 'is' unsettles us, and this is perhaps deliberate. These matters aren't cosily over and done with. They're still current, still potent, still perilous. Nothing in Brookner is ever quite safe: even a reread is rarely a comforting experience.