Thank you for your question. The demigods got to Hades the same way they got to Ares and Artemis. Teleportation and Steele. Hades was already missing before Tantalus was taken to the Underworld, which is why Ares wasn’t around to help out when Tantalus charmed Aphrodite at the campfire. Tantalus would have communicated to the island to have them drop the shield long enough to deposit Hades, but the shield casters wouldn’t have necesserily known what was brought through.

Hades and Persephone are going to be just fine. For humans, the line between the living and the dead would be an insurmountable obstacle. But for gods, particularly powerful gods, especially gods who rule the underworld, the divide isn’t as sharp. As a goddess fully vested in her powers, Persephone can interact with souls. Hypnos and Hera are both dead, too, and they’ve interacted with other characters. The biggest change for them is that he can’t leave the Underworld and as the goddess of spring, she has to spend a chunk of time there. I wrote that outcome as a callback to the original myth where the two live apart half the time. But at the end of the day, they’re just like any other couple that doesn’t spend their working hours together, albeit a couple who work in fields that require travel. Spring may bring longer business trips, but she’ll have more time off in the winter to make up for it.

I’ll definitely be exploring more of those obstacles in the Artemis trilogy, but I can promise you, relationship wise, they’re in a good place.

Hope this answered your questions. Feel free to reach back out any time.