It was commonly agreed upon that it all started with the cans.
Hamburger would laugh and talk about the multicolored bits of metal that took up most of the room in Cola's nest. Sharp and messy, stinky with orange rust that clung to his friend's scales in the morning and changed his scent to acid. It was funny how protective he was over them, keeping them till they broke away to nothing in the saltwater. Cola would always mourn and Hamburger would pat his back, agree to help him look for more, make his friend smile and preen again.
Gingerbread figured it was because of Cola's mother. She had loved to collect the silly human junk too. There were memories of playdates, her delicate guppy fins scraped raw by "spowns" and "fawks". Cola had that in him, the urge to hoard. When they were older, not yet adults but not minnows any longer, she had snatched one of his favored red and white cans from his hand and crushed it. 'Grow up!' She had told him, and when his face fell she felt a tug in her chest. She did not apologize but it still dwells on her mind how she found Cola later, leaving human things in his mother's old nest. A shrine to the dead and rotted.
Steak and Red Wine argued about their stances on the cans. Steak was of the mind that when Cola had snuck out of their borders, broken the rules of the shoal for human rubbish, is where it had started. Cola was a fine young mer, of age this year to sing his Song and choose a mate, so why was he being such a troublemaker suddenly? Red Wine would just tutt, say Cola had always been that way, was much like Steak's sister had- ah, and then the argument would start.
For Cola it started with cans and ended with cans. They were shining jewels to him, a reminder of a long passed mother, his namesake, who his father had wanted him to be. It was his lost home that ached in his blood and the Song that didn't sound right to his own ears. They were comforts as much to fill his time as to distract from how useless he really was. Too small, too weak, fins too odd shaped and dull to be pretty- he tended to the refuse like it might mend his very soul if he tried long enough.
For Cola it started with cans that danced in sunlight and floated on the waves.
For Sweet Tofu it started with a single can that fell too far for Sun Mer to venture.