There are five characters you can find in Saturated Dreamers.
One is a human, named Mercedes. She's a scientist, and has red hair. She pilots the |Leta|, and
One is a Lake human, named Venus. She was found in the Lake by the humans, and Mercedes takes care of her. She can live in the lake without being killed, and can understand the creatures of the Lake, who seem to avoid harming her. Venus can connect with the creatures. You find her early in the game.
One is NeoTheo. He used to be human, but no longer is, because the Lake killed him. But at least the Lake also brought him back to life, with creatures inside him, which give him monstrous looks, but a kindly personality. Is the real Theo even still inside? He must be, because NeoTheo still knows how to engineer the |Leta| and install and upgrade its functions. He's somewhere in the Lake, Mercedes and Venus can find him.
One is Icks. He is neither human nor Lake human, but looks human. What is he? He speaks in strange words, almost a baby language, and knows how to do many things. He has fish gills, and can change his form and grow wings when he wants to. He can guide Mercedes and Venus through the Lake, and explain the different parts of it. He's somewhere in the Lake, Mercedes and Venus can find him.
One is Spare Moment. He is also neither human nor Lake human, but not the same type of thing as Icks is. He has green skin. He is older than Icks, about a few million years older. He offers them assistance: he tells them where to go, and what they should do if they want to get back to the Duck Blind, although his words are hard to understand. Is he like a guardian angel to them? He appears on the |Leta| mysteriously at one point, after Mercedes and Venus have explored enough of the Lake.