A curious mind might set it's eyes on something and wonder what it is capable of. What can, say, a living being take before it breaks? Testing limits is always the frontier of human knowledge and of science. How far can one go? What does one have to do to truly attain mastery of something? People and animals can make themselves a nuisance to those who would be around them. Animals, however, do not have a moral burden placed on them - they may only do what is in their nature. Like a rat may burrow and undermine a small house with good people living inside, taking crumbs from behind the stairs. With how many rodents exist you would assume some kind of uniqueness applies to them. Funnily enough many of them suffer in the same way, gasp for air the same way and ultimately die the same way. All of them roll on to their side, clawing the air and might press themselves against a wall. Rat poison is suprisingly effective.
Thing is, you couldn't just leave this magic blue powder outside their nest. They had to ingest it and quite frankly - rat's prefer the finer things in life. You know, cheese, crumbs and insects. It is in knowing what your enemy desires that you may trap him. Vincent learned this when young. Every day he would wait near the door just beneath the stairs as he knew that on the other side of that door down to the right hand side layed some bricks that, due to water damage, had become weak and brittle over the years. This blue powder on it's own would not work, he would come down the next morning to see little rat feet marks but no dead rat. You must entice your enemy with a prize they cannot resist.
The second time that Vincent came down that morning he was met with the reward he had sown just hours earlier and he had come to reap. A baby rat. Not the prize he had been looking for. The adult rats can still spread and this was not good enough. He had another lesson to learn. If you're going to kill the king, make sure you do it as he might just come back to get you. Vincent would never see a rat in his house again though. They had left out. This was a problem that he didn't know he had. The king had gone to make someone else pay. A few years later a neighbour of his would have their jugular bitten into by a rat they had cornered in their kitchen. One could only assume these were descended from the rats in Vincent's home given how close by it was.
It was this experience that led Vincent into thirsting for knowledge. He could see rat's everywhere, people who he once called friends, criminals he had seen, even his own father. These are vermin. There was a clear distinction for Vincent though. He was not angered or upset by their presence, this was something much deeper. Disgust. Utter dsigust. In his spare time he would work on smaller animals. Bigger than rats this time though. A dog that kept on barking in the early morning. It just wouldn't shut up. He had no choice but to throw a sleeping pill stuffed sausage over the fence. Man's best friend didn't wake up.
His fascination led him into pursuing Chemistry at a degree level. His work brought him to Ukraine just before the Russian annexation of the Crimea. He bounced around the region doing small tasks for some money so that he might be able to set up his own chemical processing company just North of Novodmitrovsk. There were some local suppliers and the rent was cheap.
The outbreak might just have been the 'break' that Vincent was looking for. An opportunity to study what he thought was biological warfare on what seemed to be a global scale. He could not be happier.