User blog comment:The Milkman/No Love For Leviathan?/@comment-4947725-20120917050702/@comment-2228120-20120917195824

"They've been hiding from the Reapers. They were driven to near-extinction, and there are thousands of Reapers. While they can deal with a single Reaper, it's unlikely that they would stand a chance if the entire Reaper fleet discovered them." One just has to wonder about the speed of their reproduction rate, as compared to the Reapers who produce one every 50,000 years. Even when starting from scratch, the Leviathans should have safely surpassed them within a couple of cycles while the Reapers weren't so numerous yet.