He needs air.
That's all he can think of as long pale fingers brush his thighs, ghost over his chest - he needs air, he needs to breathe. But if Elrond is as kind as summer, then Thranduil is the ocean, deep and wild and dark and infinitely complicated, and Elrond is drowning in the stormy Pacific that is Thranduil, drowning in the currents and riptides that make up his lover.
"I need you," he whispers, and he means it. He needs to breathe but he needs Thranduil even more than that, he doesn't care that he's drowning.
Because he loves this, the feeling of letting go of any kind of control, Elrond loves it and Thranduil knows. That's why they keep coming back: Thranduil for the rush of power and the sweetness of summer, and Elrond because here he doesn't have to be strong for anybody, he can lose himself as summer is swept away and forget as the ocean takes its place.
He needs air.
Notes:
You can really tell I live in Northern California here.
The beaches here, when they aren't cod and foggy, are cold and windy. The water is freezing cold (unless you're my crazy friend from Alaska), but even if it wasn't we wouldn't go in because of the riptides - oh, and the sharks.
WE ARE NOT SO CAL. If you plan to visit the beach, know the difference.