Progenitor

Reborn as the irresistible Progenitor, a World War 2 veteran is out to spread the next stage of human evolution. His new, alien-built body exudes pheromones which make every woman around him want him. But his altered genetics have added a few optimizations to the breeding process along the way. This 22,000+ word novella involves lots of vaginal sex, rapid pregnancy, egg-laying, and object insertion.