I think getting fucked by Shadow Lugia would be insane. So angry, carrying so much pain and hatred. Taking it out on you, tail lashing as they pin you down with their claws, beak parted with heavy breaths when they haven't even started yet, red eyes blown wide.
Their tongue shoves in your mouth, and whenever they pull back its to cover your neck and shoulders in nips. They mantle you, wings spreading to cover you and keep you beneath them. They're rough with you, they need to be in you or you in them and they don't really care which or how.
They're much bigger than you and in complete control, something they remind you with via every sharp nip and slam down of their hips, tail thrashing behind them until they're done with you, until all that energy and anger has been worked off. By the end, you're fucking exhausted. Too exhausted to do anything except accept them curling around you, shoving their head into your chest, cautious of their sharp horns, wrap your arms around their head and neck as their tail curls around your leg.
The door to their heart isn't open. Won't be for a while. But they're certainly enjoying you, getting more than a little satisfaction out of it - and so are you. And judging by the way their one open eye is looking at you, round two won't be far off. You hope you have the energy to take it.