The other transformation his body was undergoing didn't even register, so compulsive his need to inhale.
He was vaguely aware of his little brother's wails of despair, his cries for help; help for his big brother who was having some sort of seizure.
Just when Dean thought he was about to die, the agony in his body unbearable, he found himself breaking water, the azure sky appearing like a benevolent mother above him.
Once again his lungs pleaded for a breath, a attempt in extremis to keep his body alive, and contrary to all Dean could have expected, his lungs filled with the dry air of the upper world; that world where the merpeople could only resist for a handful of minutes at a time without the need to plunge back into the life-giving ocean.
The respiratory organs which had once filtered oxygen from the warm ocean, were now, between water-filled vomits, breathing in the air with a relieved rhythm.
“Dean,” his father's gruff voice sounded in his ear, “Are you okay, son? You breathing now?”
Dean nodded, and he heard his parent's sigh of relief.
“What happened to me, dad?” he asked confused, his panicked breaths evening out to shaky puffs.
“I don't know, son. When I heard Sam's shouts, I came swimming. And when I saw you, I guessed what the problem was.”
“What are you talking about, Dad? What problem?”
“You don't feel any different? “ John asked with a preoccupied glance.
“I couldn't breathe. That's all I was thinking about.”
“Run your hands down your body, son.”
Dean frowned and went to flip up his tail, but to his horror, all that moved were two human legs.
His tail, his awesome, muscular tail had disappeared and in its place were two spindly, useless limbs.
“Dad?” Dean's face was a picture of despair as he searched out his father's eyes.
John ducked his head under water to take a breath, and to wonder himself at what the fuck had happened to his eldest.
It's not that John didn't know what Dean had become.
He'd been a human himself before he'd fallen in love with the beautiful mermaid he'd caught sight of in a rocky pool, and for whose love he'd left behind the dry world to live beneath the ocean with her.
But that had been possible only due to a witch's spell, a transformation one, which he'd agreed to undergo.
John had never had any regrets. He loved Mary with all his heart, and adored the two merbabies he'd had with her.
The why of Dean's transformation into a human was a mystery to him. But, at least his son was alive, even if in another form. He hadn't lost him to death, and that could only be a plus.
As his head came back up, he sensed his wife's presence at his side.
She'd been occupied with the preparations for Dean's coming of age, his entry into adulthood, the Crossover ceremony which every child went through on his twelfth birthday, and had been told about what had happened by a terrified Sammy.
“Dean,” she said, pulling her eldest into her arms. “Oh, Dean!”
“Mom,“ the boy murmured, tears filling his green eyes.”Mom, what's wrong with me?”
Mary took a deep breath, aware of John's eyes on her, and of a worried Sam, who'd popped up at her side.
“I'm not sure, “ she sighed. “But I'm afraid I might have an idea.”
Three pairs of eyes stared at her. Now that Dean was safe, even in this changed state, the focus was on the why it had happened.
And by Mary's cowed expression, she knew something about it.
“Mary?” John asked.
“I'm not going to say until I'm sure,” she said, playing for time. “I need to consult a person first.”
“But you suspect what the reason might be?”
“Perhaps, “ she acknowledged, remembering the sea-witch's warning from years before. “But we have a more urgent problem now. If Dean is human, then it's impossible for him to live as he has before.”
“Mom, no! “ Sam piped up. “I don't want to be without Dean.”
He threw himself onto his brother hugging him.
Dean realised he was treading water, floating as he'd seen humans do. He no longer had the merman capacities of before.
It was the first time his situation had really registered.
He was different, he could no longer live beneath the seas with his family.
Now he was an outcast.
His arms tightened around his little brother, and his eyes filled with tears once more.