Why does General Grievous say “Ah yes, the negotiator?”

Question

When Obi-Wan Kenobi and Anakin Skywalker enter the bridge of General Grievous’ ship near the beginning of Star Wars Episode III: Revenge of the Sith, Grievous says

“Ah yes, the negotiator.”

I don’t know if he meant Obi-Wan, Anakin, or maybe even Palpatine, but regardless I don’t understand… Who is the negotiator?

And in fact, there didn't seem to be any negotiating at all, or any plans for there to be any.

The Jedi came to rescue Palpatine, and it seems that they didn't plan to do so peacefully. They entered the ship forcefully after destroying multiple separatist space droids, then immediately fought several battle droids, and killed Count Dooku.

It seems that they never planned to negotiate at all.

Why did he say this line then?

Answer 1

Because that's his nickname out in the galaxy.

Obi-Wan's diplomatic skills, specifically his reputation for preventing and stopping battles without using a single weapon, earn him the appellation "The Negotiator."

_{^{Ultimate Star Wars - New edition}}

The original script indicates this with a capital N.

GENERAL GRIEVOUS: Oh yes. General Kenobi, the Negotiator. We've been waiting for you. That wasn't much of a rescue.

The film's junior novelisation references this in the fight scene between Kenobi and Anakin

But when he looked back, Anakin was standing on a worker droid, coming up fast. “Your combat skills have always been poor,” he taunted. “You’re called the Negotiator because you can’t fight!”

_{^{Revenge of the Sith: Junior Novelisation}}

and the main novelisation mentions that his nickname is something of a joke among the senior Jedi.

“Masters, Masters, please,” Obi-Wan said. He looked from one to the other and inclined his head respectfully. “Perhaps there is a middle way.”

“Ah, of course: Kenobi the Negotiator.” Mace Windu settled back into his seating pod. “I should have guessed. That is why you asked for this meeting, isn’t it? To mediate our differences. If you can.”

_{^{Revenge of the Sith: Novelisation}}

Answer 2

The "Negotiations" are a euphemism for fighting.

The theme of "Negotiations" with relevance to Anakin and Obi-Wan appears in both The Phantom Menace and Attack of the Clones. At the start of The Phantom Menace, Obi-wan is accompanying Qui-Gon Jin to Naboo to negotiate a peace treaty and the end of the Trade Federation blockade of the planet. Then the Trade Federation attack them, which leads to Obi-Wan's quip, "you were right about one thing, Master: the negotiations were short". See this clip for details.

As a call back to this, in Attack of the Clones, Anakin relates stories of his adventures with Obi-wan during which they participated in "aggressive negotiations" or "negotiations with a light sabre". See this

and this...

So in Revenge of the Sith, Grevious' comment calls back to this theme. Off screen either Anakin or Obi-Wan (or possibly both) have gained a reputation for being formidable opponents. Grevious is being sarcastic, as he has killed Jedi before and he does not think them a threat to him.

As to which of them he is actually addressing the script states,

62 EXT. BRIDGE-TRADE FEDERATION CRUISER

OBI-WAN, ANAKIN, PALPATINE, and ARTOO are captured by GENERAL GRIEVOUS. They stand before the ALIEN DROID GENERAL.

GENERAL GRIEVOUS: Oh yes. General Kenobi, the Negotiator. We've been waiting for you. That wasn't much of a rescue.

A BATTLE DROID walks to GENERAL GRIEVOUS and hands him the JEDI'S lightsabers.