One of the few things on which good and evil agree is the need to preserve the Grand Design against anything that could possibly throw it off balance. For instance, the Elders were violently opposed to Piper marrying Leo because they feared allowing a Whitelighter to marry a Charmed One would create too great a concentration of power. When Cole Turner got wind of Piper and Leo's plans to get married under the Elders' noses, he alerted the Triad, who immediately alerted the Elders.