Cleopatra by H. Rider Haggard

Now I, Harmachis, must make speed with my task, setting down that which is permitted as shortly as may be, and leaving much untold. For of this I am warned, that Doom draws on and my days are wellnigh sped. After the drawing forth of Antony from the Timonium came that time of heavy quiet which heralds the rising of the desert wind. Antony and Cleopatra once again gave themselves up to luxury, and night by night feasted in splendour at the palace. They sent ambassadors to Caesar; but Caesar would have none of them; and, this hope being gone, they turned their minds to the defence of Alexandria. Men were gathered, ships were built, and a great force was made ready against the coming of Caesar.

And now, aided by Charmion, I began my last work of hate and vengeance. I wormed myself deep into the secrets of the palace, counselling all things for evil. I bade Cleopatra keep Antony gay, lest he should brood upon his sorrows: and thus she sapped his strength and energy with luxury and wine. I gave him of my draughts -- draughts that sank his soul in dreams of happiness and power, leaving him to wake to a heavier misery. Soon, without my healing medicine he could not sleep, and thus, being ever at his side, I bound his weakened will to mine, till at last he would do little if I said not "It is well. " Cleopatra, also grown very superstitious, leaned much upon me; for I prophesied falsely to her in secret.