Nessie is Eddie's girlfriend. Yes it's true, the flamboyant, rainbow loving, high pitch voiced man lover has a girlfriend. It was as much of a surprise to him as it might be to you.
Eddie was raised by humans in a science lab. The scientists of a special research lab performed tests on Eddie that allowed him to gain mass knowledge of science. Because of this Ed doesn't remember much of his life in that time except that the females there were mean and would bite him, and the food the scientists fed him was made of fish so he stopped eating fish cause they were his friends. When an animal rights group came to shut down the lab, they were going to just kill all the fish (no fur? Tough luck). One of the assistants who had trained Ed do eat carrots instead of fish parts, picked up Ed and tossed him into the ocean, in hopes he'd make it on his own.
Ed did make it very well. It took a while for other fish to trust him, and started getting work at a gay bar and hang out with other boys. But his need to be a humanitarian lead him to meet Nessie at a non-profit organization made to help better life of the reef folks. Eddie worked in the gay bar until the day his boyfriend beat him up, and Nessie saved him. All of Ed's other guy friends blamed Ed for his boyfriend going to jail, so Ed ditched that job and lived with Nessie for a bit. The two of them worked for the non-profit organization to stop people like Gulper building and tearing out reefs and nature preserves. During this time Ed gets his cave home and moves in there, but Nessie stays at her house cause it's closer to where she works.
Not long after all that the two of them decide to start a little kids show on the public access channel. The more they worked together the more Ed liked Nessie every day. He wasn't sure what feelings he was having for her, but he knew there there wasn't any other woman he ever wanted to be with. Nessie liked him back, but if they were going to pitch their show to a large network, they couldn't start a family together. Only a few weeks after this announcement, a fisherman bombs the reef and takes out the whole west side of the town, as well as the public access station, the gay bar Ed used to work at, the Non-Profit, and Nessie's house. Nessie went missing after that.
3 years after that Ed pitches the show to a local network in honor of Nessie. The show we see starts 2 years after that (5 years after the explosion). I do have a future for Nessie MUCH later in the shows development, but that could be a story for another day...*spoiler*she does come back.