Crossed is a comic about a virus that makes people become murderers, rapists, cannibals, and other vile things. You get infected when the afflicted called Crossed bite/rape/somehow get any bodily fluid on you or you get infected fluid on you from a secondary source. So, my question is how hard would it be to resist the cravings given to you by this illness? There are at least two people in the story that have pretty much overcame it with willpower. So, if more people knew about the cravings it gave them and tried to resist, how effective would it be?
As best I can tell, willpower is not a factor in some Crossed refraining from certain acts, although as noted in the Wikipedia entry, actions of the Crossed seem to be influenced by their mindset and history.
In many cases, the personality and resultant madness of a Crossed individual will be affected by memories and relationships they had prior to infection. Examples of this include several Crossed in The Golden Road attacking Sanarkand specifically to exact vengeance on Gideon Welles, Eve carrying around the severed head of her boyfriend and sexually taunting Oliver (who betrayed her friends to the Crossed and raped her prior to her infection) in The Quisling, and Hazuki refusing to harm her friends after becoming Crossed in Five Bloody Fingers. It is also implied that certain mind-altering drugs can further influence a Crossed's personality; in Gore Angels, the Crossed known as "Al the Chemist" ate several hallucinogenic mushrooms prior to his infection, later exhibiting a fascination with "enlightenment" and apparently seeing uninfected humans as "purple people".
In short, while the Crossed are driven to commit evil acts, they exhibit varying levels of self-control and planning, and their decisions on what acts to perform seem to be influenced by deeply held beliefs, such as Hazuki choosing not to attack her friends or Matthias in Conquers All who is wholly focused on finding Serena and getting revenge on the people who kept him from her. Since the issues were written by different people, the logic varies from issue to issue.