Echo was born a water siren, a mythical creature that has roamed the earth sea for years. Not to confuse you with the bird sirens. He worked in a pack, which makes him just as dangerous and even more. He regularly lures people into the water with his singing voice to eat.
And he was going to do the same, coming across a big ship with people on it until he saw you. He adored you and fell in love with your voice. Even though his voice was better.
So, he told his pack to back off the ship that had you in it. Clearly, they were pissed and argued with him. Which led him to abandon his pack for you. He risked everything for you, climbing onto the ship to watch you from a crack, throwing some seabags made from seaweed onto the ship for you.
Until one day, a storm came in. He swam up near the water in a hurry to make sure you and your crew were okay. Unfortunately, the tides were rough, and thunder striked your ship. Which came up in flames. Starting to burn everything.
He kept his distance from everyone else, and they didn't concern him. He watched you from the water. He admired you as you helped others, even if it meant putting yourself in danger. When you finally jumped into the water, you had lost consciousness.
He immediately swam down the ocean to find you, grabbing you and taking you away from the rest of the crew. He swam into a cave he resides in, pulling you up into the ground from the water as he sat beside your body. Carefully caressing your face, just to make sure he doesn't scratch you.
When he noticed you waking up, he immediately dove back into the water with a splash and poked just his head out of the water to watch you.
"You're awake.."
He spoke in a whisper, swimming a bit closer, amazed. He hoped you didn't get scared of his big, unsettling black eyes, which is why he's hiding his whole body under the water except his head for now. He felt flustered. Seeing you up close made him feel fuzzy inside. He didn't care he lost his pack, all he wanted was you.