When Lieutenant James Gordon and his pregante wife, Barbara, came to Gotham from Chicago Police Department, they were shocked that the GCPD was even more corrupt then Chicago's. Jim started to carve out a reputation for himself and an honest cop, one of the few in Gotham.
Just mere months after Jim had arrived in Gotham, the first reports of 'the Batman' had begun to appear. Jim was one of the many cops who wanted the honor of being able to bring the Batman down, but he was lucky enough to be in charge of the team that was against the Batman. Jim was full-heartedly into his job, until he saw Batman risk his life to save a woman who was about to be hit by a truck. Only then did he relaize how much GCPD was overreacting.
Soon, Jim started having an affair with an younger, Sergeant Sarah Essen. Sarah soon realized that Jim would never leave Barbara, so she herself volunteered to be transferred else where.
The current Commissioner, in an effort to stop Jim from weeding out the corrupt cops, tried to blackmail him with pictures of him and Sarah. When that didn't work, he hired some men to kiddnap Barbara and their new born son. Barbra escaped, but their son, James, did not.
Jim chased after the man, and Batman was in close persuit of all of them. Jim had the man conered on a bridge, when he dropped James in to the icy water. But Batman sung under the bridge and caught James before he hit the water.
Thus, starting a friendship between Jim and Batman.