I have noticed a trend in "Redwall" stories. My dad reads Redwall and so far has read Mossflower, Redwall, Mattimeo, and is reading Mariel of Redwall right now. He has noted that in all of those the villains are/go insane.
In Redwall, Cluny the Scourge falls from out of a tree. Afterwards, he begins acting strangly. Some people say he was faking insanity, I saw he was insane. He also has re-accuring dreams of Martin/Matthias. I would call his behaviors one of someone who is crazy.
In Mattimeo, Slagarappears obbsessed with making Mattimeo suffer; he lies to him about his experience in Redwall, he shows him his disgusting maimed face and just acts like someone who has lost their marbles! If you have watched the Nelvana TV version of Mattimeo, you will note how crazed Slagar seems thoughout the entire thing. one of the reasons I like that season is because they captured his insanity well.
In Mariel of Redwall, Gabool is just plain crazy. He begins to suspect mutineers and cannot sleep. Sleep deprivation is one of the reasons he was so crazy; he could not sleep without having terrifying dreams of badgers.
Other villians seem to be in a panicked/crazed state by the end of the story. In Loamhedge, Raga Bol has a reacurring dream of Lonna Bowstripe even though he believes he has killed him. He was terrified when Lonna attacked.
In Martin the Warrior, Badrang was also very panicked when Martin killed him. Captain Trauman Clogg, another antagonist in Martin the Warrior also loses his marbles and begins to talk to the corpses of Badrang and others inside after the attacked.
It is apparent that the villains in many Redwall stories begin to lose their mental health as the story progresses. Be it the in their dreams, sheer panic, or otherwise. Many of the antagonists decline throughout the story.