So, this is what I've been able to piece together so far. Please feel free to add your two cents or give your own hypothesis. I'm all ears - love this game :D

--Academy of Sciences
After unrest in the Telluric Republican government, the Nationalist proletariat and their leader, Chancellor K., are pledged the military force of the country. The outbreak of the plague leads to mistrust of the scientific community, and the Chancellor soon begins to discredit their work and the germ theory. Shortly after a gathering outside the Academy of Sciences, Telluric's citizens are angered and form a violent mob, destroying the Academy. In a bid to continue their plague research undisturbed, the survivng scientists plan to sail to the island Eden, where they suspect a cure can be synthesised.

--The Scientists & Herbert--
The scientists arrive at Eden with such classy names as Dagless, Sanchez and Cornelius embarking to different parts of the island to conduct their research and find the components of the cure.
(I haven't been paying much attention to individual stories apart from Herbert, Oswaldt and Sanchez - feel free to supplement if you think there's other stuff that needs telling :)

Progress goes well for some time; the men tackle the challenges of the island as they come, finding each ingredient over an unknown period of time [bold] with a conspicuous lack of monster tracking them down [/bold]. All three of the primary cure ingredients were at some point successfully produced, though there is no remnant of these "prototypes" by the time Robert Hughes shows up...

One researcher, Herbert, stationed at Outpost Vega in the West, begins to suffer due to his (perhaps undiagnosed) affliction with the plague. Despite his attempts to continue his work, even successfully locating one key specimen, he begins to suffer from auditory and visual hallucinations manifested in the form of an unreal, deformed "dervish" of a beast. He begins to look into anti-hallucination drugs, synthesising them from such common flowers as the Sunflower Variant found throughout the island.

(NOTE THAT THE SUGGESTED PLANTS [bold] DO NOT [/bold] PRODUCE ANTI-HALLUCINATION DRUGS (AT LEAST FOR ME - NEED CONFIRMATION)

Whether due to malfunctioning, inept anti-hallucination drugs or simply the continued madness of the plague, Herbert takes his obsession with the beast up a notch from paintings, and engages in a killing spree throughout the island for motives unknown. He tracks down his fellow scientists and kills them, showing brief moments of horror and lucidity throughout, before disappearing from Eden, leaving no trace but a trail of blood and words.

--Robert Hughes--

A plague-ridden man named Robert Hughes washes ashore on Eden. Hoping to find the enclave of "enlightened men", he instead finds the remains of countless murders and the notes the deceased left behind. Haunted by the same plague-induced monstrosity as Herbert, Robert must connect the dots and escape his fate as the beast grows ever stronger around him...