In the Wheel of Time there are many references to the dagger that Mat takes from Shadar Logoth corrupting people and turning them against even their closest companions.
There are too many references to mention, but the two main people the dagger taints is Mat and Padan Fain. Mat thankfully is freed from his connection to the dagger, and Padan Fain's whole story line involves the dagger and being tainted and therefore influencing people near him (a la the Whitecloaks in The Shadow Rising, and a few more people).
Because there is such a fear of touching the dagger, or even being near someone who holds it for too long, I was wondering why the Horn of Valere was never tainted in the same way. It is locked in the same box as the dagger for just as long as Fain had it or even longer, but yet when Mat blows the Horn to summon the great heroes of the Pattern there is no mention of them being affected.
When summoned after Mat blows the Horn Artur Hawkwing says:
"We have come to the Horn, but we must follow the banner. And the Dragon."
And it is revealed that the heroes of the Horn would never follow the Dark, only the Light.
Was this always the case? Or were there plans for the heroes of the Pattern to be tainted by the dagger in the same way that Mat and Padan Fain were? Or are the heroes and the Horn always resistant to the corruption of the dagger?