What is one complication that happened in Maximum Ride 1?

One complication that happened in Maximum Ride 1 is that the children were exposed to a deadly virus called the "Re-Evolutionary Virus." This virus was created by their enemy, Jeb Batchelder, and was designed to kill humans. The children were infected with the virus as a result of a raid on their home by Jeb's forces, and they had to fight to survive the effects of the virus while also trying to stop Jeb from using it against the rest of the world.