How did Palpatine know of Anakin's vision?

Question

Palpatine tempted Anakin with ways to save loved ones from death, but for that to be effective he must first know of Anakin's vision. How did he learn of it? I have doubts on whether Anakin had told Palpatine of it himself. Anakin knew his marriage is forbidden by the Jedi code, so he did not share the vision with even Obi-Wan, going directly to Yoda - the perceived wisest of the order especially in matters of visions and the Force - out of sheer desperation to protect Padme. He did not tell Palpatine about his marriage (Palpatine learnt of it from an informant) so I doubt he would consult someone who is at that point still portraying himself as a non-Force-wielder.

The only way, to my eyes, for Anakin to tell Palpatine about the vision is if Palpatine first displays a relevant, applicable knowledge of the Force - assumed here to be knowledge of saving one from death - but the only way Palpatine would deem it useful to reveal such knowledge in tempting Anakin while risking revealing too much about himself would be if he knows of Anakin's vision first. A circular logic here. What gives?

Answer 1

Palpatine adds 2+2 together and comes up (unsurprisingly) with 4.

We know from the film's official novelisation that Palpatine is very well aware of Anakin's marriage to Padmé

“Anakin, Padme was my Queen; I was her ambassador to the Senate. Naboo is my home. You of all people know how I value loyalty and friendship; do you think I have no friends among the civil clergy in Theed? Your secret ceremony has never been secret. Not from me, at any rate. I have always been very happy for you both.” - _{^{Star Wars: Revenge of the Sith - Official Novelisation}}

During the squid ballet scene, Palpatine then tempts Anakin with a range of things; Political power (which bores him), greater knowledge of the Force (which he's only mildly interested in) and finally the ability to extend his own life. During this conversation, the conversation takes an odd turn and Anakin reveals his true desire. Rather than showing an interest in his own mortality, Anakin wants to know about the ability to extend the life of a loved one.

"It’s a Sith legend, of a Dark Lord who had turned his sight inward so deeply that he had come to comprehend, and master life itself. And-because the two are one, when seen clearly enough-death itself.” Anakin sat up. Was he actually hearing this? “He could keep someone safe from death?”

At that point, Palpatine has Anakin pegged. He's clearly very concerned about his wife dying. Given her young age and Anakin's proclivity with the Force, it's reasonably likely that this relates to a Force vision rather than general paranoia.

Answer 2

Edits because I found my copy of the novelization of 'Revenge of the Sith'.

First like my original post Palpatine frequently meeting with informally Anakin before the his vision. Superficially to have an unofficial back channel to the Jedi. Though almost certainly because Palpatine wanted to influence Anakin for his own purposes. There is a mention that Palpatine had attempted to give many lessons to Anakin on politics during their meetings.

In the novelization he never actually tells Palpatine about his vision. He does tell Padme though. The novel also doesn't give any clear answer about how Palpatine knows, or chose what to say during the meeting with Anakin.

I think we are left with a couple possibilities about what happened.

• Palpatine had Anakin/Padme bugged, and picked up on the conversation.
• Palpatine didn't actually know about the vision at all, he sense Anakin's unease and he was somehow motivated by the force to tell Anakin about Darth Plagueis.

Answer 3

It's implied that Palpatine himself planted the vision into Anakin's dreams.

In this scene, you can clearly see Palpatine smirking when talking about saving Padme:

He knew that he had made Anakin completely rely on him by planting the vision into the latter's dreams. You can clearly see Palpatine's expression when Anakin was telling Windu that he needed Palpatine in this scene:

Palpatine was feeling happy because he knew that his plan had succeeded. Hence he confidently told Grievous early on in Revenge of the Sith that he was going to have a new apprentice: