After you select the word "devolve", a syringe come into view on the screen, stabbing the fish right behind the gills. Your father squirms helplessly, in obvious distress as a green fluid is injected from the syringe into his body.
The hands set the rainbow trout onto the ground, allowing it to flop around on the ground in pain. From the high definition you can see as his scales grow thicker and larger, his body broadening while simultanously flattening out somewhat. His jaws open and close as his head changes like his body, flattening out and growing wide like a guitar pick. His eyes move up towards the top of his head with the reformation. His head looks like a giant armored arrowhead, fanning outward.
His eyes complete their migration to nearly the top of his armored head. His jaws retreating underneath the head plate, devolving to a jawless mouth opening on the bottom. The scaly fins that were once his arms flit about uselessly just behind his head plate, the rest of his armored body tapering out behind him into a tail with a large fin at the end. You notice his pectoral fins, all that had remained of his human legs, have completely retreated into his body.
The primitive and heavily armored fish moves slowly on the ground now, looking much like a giant armored tadpole stuck out of water.
You wonder if your father is still in there as you stare at the ancient creature on the screen. Somehow you know he is. Just like your brother the rat, you can somehow sense the awareness his beady eyes. The fear and confusion too.
The digitized voice comes onto the speakers.
"Cephalaspis magnificans," the voice explain, "early ancestor of modern bony fish. Lived 400 million years ago. Long since extince."
You stare helplessly as the voice takes on a much more sinister tone.
"Now, choose his fate"
The following options pop up on the screen: