Loki

Loki nodded. "Unfasten these chains," he told them. "I'll do it. I'll need Freya's falcon-feather cloak, though."
"My cloak?" asked Freya.
"I'm afraid so."
Freya walked stiffly away and returned with a cloak covered with falcon feathers. Loki's chains were unfasteend, and he reached for the cloak.
"Don't thin you can just fly off and never return," said Thor, and he stroked his white beard meaningfully.

[...]

Then Loki wrapped the falcon cloak tightly about himself and, in falcon form, flapped his wings and rose, faster even than an eagle, and was gone, flying north, towards the lands of the frost giants.