If that evil character was the only evil character in battle when the convert was played, the EC gets special initiative to interrupt the negate or convert effect. Only cards that interrupt or negate the card removing him from battle can be played during special initiative, but he can still play enhancements of the brigade he was before he was converted during the special initiative. If the special initiative passes (so he either couldn't or chose not to interrupt or negate the convert), then the evil character is now a hero, leaves battle (because heroes cannot fight heroes except in side battles), and from that point on can only play enhancements of his new brigade color.
