From the REG:
Instant Special Abilities > Convert > How to Use
Evil Characters may only be converted to Hero brigade colors (i.e., blue, green, purple, red, silver, teal, white, and gold). The only exception is Saul (Ap), whose natural brigade color is multicolor when a Hero. When no color is specified on a conversion enhancement card, the character converts to the same brigade color as the conversion enhancement card. The converted character remains under the control of its owner. The character reverts to its original state only if the card is returned to the draw pile, placed in the discard pile, or converted back. The character remains converted even if set aside, captured, or rescued. Rules for duplicate characters still apply.