By any means necessary. Hades caught the emphasis the second time. He knew Zeus had an idea, because the glint in the eye was there, but his brother wasn't going to say it outright. When any means meant any it was fairly obvious what Zeus meant. If he had an idea that wasn't morally dubious Zeus would have just said it outright. He'd want it down in the record that he was the one who came up with the brilliant idea. Zeus's idea for Hades to get that time he needed was not the going to be smiled upon by the other Olympians. Hades knew, because he had the same idea. It was the only idea that he had.
Since Demeter would not give her daughter up willingly, Hades would have to get her unwillingly. Demeter wouldn't let him court her. Even if she would, there was no guarantee that would work. Hades had never courted anyone before. Everyone on Olympus had courted everyone before. Probably at least twice. He wouldn't respond well to that pressure, or the eyes on them. He'd lose, and Hades knew he couldn't afford to lose when it came to this. If he could, he wouldn't be asking his little brother for advice. Hades needed time with her alone. He needed it to be in his element. He needed it to be far far away from Demeter.
Hades nodded slowly. “By any means.” If neither of them actually said the words, they could avoid implication. Well, Zeus could. Hades, by virtue of acting on this advice couldn't. Later he'd come to his senses and think about the consequences, and the ethics, but Hades didn't have his senses then. By that point they'd left. By that point, Hades was ready for any means. “And you'll back me on this?” he asked. Hades waited for some kind of confirmation, and they went into the specifics a bit. After they'd finished, Hades nodded. “Thank you for the consult.”
He disappeared shortly after that. Zeus had been more helpful than Hades had expected. They worked surprisingly well together when they were actually working together. Hades didn't think they'd done that since the war ended. It was kind of sad. Maybe Hades had been wrong about him. He didn't think that family meant anything to Zeus. Maybe it did.