How we cite our quotes: (Part.Letter.Paragraph)
Quote #1
And he would never think of exploiting the gaiety he inspires. He is perhaps something of a flatterer, but his delicacy would disarm modesty itself. (1.11.1)
Unfortunately, Madame de Tourvel is deceived by Valmont right from the start. Why do you think she's so easy to trick?
Quote #2
As for you, are you not ashamed? You put yourself to the trouble of deceiving him, and he is, notwithstanding, happier than you are. (1.15.1)
For Valmont, a successful deception is nothing to brag about. To be worthy of respect, a lie must have a successful purpose. In this case, the Marquise is lying to her current lover about her ultimate designs, but, in Valmont's estimation, her lover is receiving more benefit from the deception than she is.
Quote #3
Madame de Tourvel has charged one of her servants with obtaining news of my activities, if necessary by following me on my excursions of a morning, as far as it is possible for him to do so without being observed. (1.15.4)
Deception isn't just something the "villains" of this novel do: even the principled Madame de Tourvel will make use of minor deceptions. She wants to spy on Valmont without him knowing it. Ironically, she's doing it to uncover his deceptions.
Quote #4
You cannot imagine the tissue of unspeakable lies that diabolical shrew has fabricated around me. (1.44.16)
It's funny to hear Valmont, a satanic figure if there ever was one, complain about his enemy being diabolical. Truth is, he's not miffed because Madame de Volanges lied about him (supposedly); he's upset that he's not getting his way. Madame de Volanges' daughter pays the price for her alleged lies.
Quote #5
A carefully chosen section of these letters would show that little Volanges had made all the advances and indeed thrown herself at his head. (2.66.4)
One can lie by telling part of the truth and leaving out the whole of it. Valmont here suggests that, if revenge calls for it, he could make a selection of the correspondence between Cécile and Danceny public—a selection that would make it appear that Cécile's behavior was more scandalous than it really was. Having only part of the truth, the public would assume they knew the whole story.
Quote #6
How dare I tell the truth, when sincerity may be my ruin with you? (2.68.1)
Valmont is crafty and clever. He knows that honesty and truthfulness matter to Madame de Tourvel. He therefore frames her request of him as a request to lie.
Quote #7
Provided with my first weapons, I practiced using them: not content to be inscrutable, it amused me to assume different disguises, and once sure of my demeanour I attended to my speech. I regulated both according to circumstances, or simply as the whim took me. (2.8.26)
The Marquise is the queen of the lie. She's practiced it from a young age and it's now second nature. It's her talent for deception that allows her to fool everyone into thinking she's a pure and respectable person.
Quote #8
In vain had I been told and had I read that it was impossible to feign the feeling [love]; I had already observed that to do so one had only to combine an actor's talents with a writer's wit. (2.81.29)
This was probably the life lesson that most enabled the Marquise to be such a success; she can totally and convincingly fake love. Valmont prides himself on that same talent but it eventually fails him.
Quote #9
In order therefore to attract one party and repel the other, I was obliged to advertise an indiscretion or two, taking as much pains to mar my reputation as I had meant to take to preserve it. (2.81.31)
Don't assume that because Madame de Merteuil is willing to admit some of her faults in addition to some of her virtues, she's an honest person. She's interested in creating an image of herself, or in this case two images meant for two different audiences.
Quote #10
No, I no longer believe in love, in honesty. Oh! what can I believe in, if Cécile has betrayed me?
Answer me then! Is it true you no longer love me? No, that is not possible. You are deluding yourself. (3.93.3-4)
Dramatic, isn't he? In his excited way, Danceny is just as manipulative as Valmont and Merteuil. If he's slightly less detestable, it's because we get the sense that maybe he's not really trying, in some cold-blooded way, to manipulate Cécile. He really does love her, but he doesn't trust her. Of course, Valmont hasn't been delivering her letters as promised, so Danceny's the victim of deceit.