Clues

The infirmary fell into silence as we digested the news. 

"The severance took less than an hour?" Blaise asked, shaking his head. "I find that hard to believe. Darach isn't some young pup that just got his wolf!"

"That's because it didn't take an hour. It has been happening for a long time." Nicole sucked in a breath, and continued to speak. "Darach's connection to his wolf was already weak to begin with, possibly from years of wolfsbane poisoning. This severance couldn't have happened in the span of an hour, if we are looking at an ordinary bond between man and wolf." 

"It was already a fraying rope, and Alpha Thorton merely delivered the final blow. Darach must have used every bit of his strength of the connection to reach you in the hopes that he could save himself. Now, his inner wolf is hanging on by the thread, which is why his healing will be slow."