How might the viceroy's colors affect monarch butterflies?

The Viceroy mimics the Monarch for a special reason. The Monarch is poisonous, and so by the Viceroy acting like it's poisonous, predators avoid it. There is one difference though, the Viceroy has a black line running across his lower hind-wings.

no^ the color of the viceroy is close to the monarchs and so at mating season it can affect them