User blog comment:TheNewProtagonist/So... dem Auras, huh?/@comment-7497475-20130823053847/@comment-4773581-20130823062645

I assume the latter, if only because they seem more primal. Or at least the stuff in the forest, anyways. There's probably smarter Grims out there.

Hell, the Grim Tiering System could be based entirely on the Grim's level of intelligence. The smarter ones are higher up and stronger while the dumber ones are lower down and weaker.