Matt was dizzy from the musky odor he was inhaling from Ben's caveman body. The smell was so intoxicating and it was beginning to affect in a more permanent manner. While Ben was changing as a result of the chronivac, Matt was changing because of Ben, meaning the changes would be permanent.
Matt was unaware of how serious his situation was. He now had a light dusting of hair on his chest and small bushes of wiry hair in his pits which were producing a much more mild body odor than Ben's. Before Matt had a chance to pull away, Ben - in his sleep - grabbed Matt with his hairy arm and held him close to his body like a sleeping pillow. Matt was now held even closer to Ben's naked caveman body, covering Matt in sweaty musk. Matt was too confused and weak to fight back; besides, Ban's new body was too strong to fight back anyways. As Matt struggled to escape, a noticeable layer of stubble began to form on Matt's face as his adam's apple dropped. Matt heard his grunting grow deeper as he struggled, leaving him with a deep baritone voice.
As Matt continued to struggle, Ben was growing aroused by the squirming, causing his new caveman dick to grow hard again and leak copious amount of precum. Matt could feel the erection brush against his abdomen, painting it with sticky musky caveman precum as well. The precum tingled as new hairs grew from it, leaving Matt with a hairy treasure trail now. In addition to that, Matt's cock was beginning to grow harder for some strange reason, its foreskin regrowing and Matt's testicles swelling in size as they devolved into a caveman state.
Matt was losing his human form fast. He needed to think of a clever solution to escape the sleeping Ben before Matt turns into a dumb caveman too!