Dennis activated his monster transformation first!
Almost immediately after he did so, one after another, all his clothes vanished off his body, like David’s had, then, his penis deflated, shrivelled up, and vanished, replaced by a covering of scales, which soon spread over his body, like his brother. The scales mostly retained the skin colour, but with a slight reddish tinge to them.
Like his brother, he gained muscle, and grew the short stumpy tail above his butt.
But to David's surprise, Dennis' feet had 4 toes, And his hands had 3 fingers, his ears pointed, and short stumpy spines grew on his back; yet instead of brown, they were blue, like the colour of his scales.
His face pushed and melded into a snout, and grew claws on his hands and feet.
Dennis was a monster, similar to his brother had been before.
Everyone was amazed.
But David was baffled about why his brother had the same tf as him, but slightly different.
Also, he was wondering what happened to his brother's clothes. "Why did your clothes disappear?" he asked his twin brother.
"MonsterMen don't wear clothes, so, us MonsterMen often strip off our clothes, or they disappear, or destroy themselves as we tf." Dennis said. "But do not worry." he added, " the clothes magically return to their owner's homes, as if they were never destroyed to begin with."