|Appearance||The Last Man on Earth|
Dr. Mercer tasked Ben and Morgan with examining Europe's Disease after it recently broke out in the US.
As the plague further and further decimated the entire world, Dr. Mercer came to work one day to find that Morgan was the only other one who showed. Morgan worried that this was the end of humanity, but Mercer assured him that mankind has survived far worse, and his and Morgan's current work was proof that humanity would survive.
Dr. Mercer's ultimate fate is unknown. He was presumably infected at some point, and either turned into a vampire or joined the new society.