The story of Neptune is almost exactly the same as that of Uranus, though less of its methane atmosphere was ionized/deatomized because it was further away. Only about forty five percent was ionized/deatomized. Rather than an ocean like Saturn, Neptune had more of an ooze formed when the heavy elements mixed with the lighter elements on their way down, eventually forming life. The surface of Neptune, like Uranus or Saturn, is a very smooth diamond sphere, with aforementioned ooze forming a waist-high soup of substances. Callisto and Europa, two of the Galilean moons in our timeline, orbit Neptune in this one.
The Tivers are massive Ursidae-esque creatures, covered fur, which varies in color depending on age and genetics. Over millions of years of brutal warfare, the fur has gone from a soft insulation material, to a hardened armor, almost like that of a porcupine. They have four fingers and toes per limb, with each phalanx bone containing a retractable claw. Over the millennium, the Tivers have gone from quadrupedal to bipedal, and have become more intelligent with that transition. While they are intelligent enough to contemplate philosophy, and build terrestrial vehicles, the Alayans have not yet reached a space-faring level of technology. Until they stole it. Hundreds of years ago, the Huraise visited Saturn, wishing to accept their neighbors with open arms, but instead were mauled and their spacecraft taken. Up until that point, they had been simple nomadic tribes, fighting each other day in and day out, but then, they found a new way of doing things; go to other planets, and beat up those guys! Indeed they did, travelling throughout Umimon, eventually coming to rule over Uranus, and engage in a massive war with the alayans, who posses enough skill and strength to combat the Alayans for hundreds of years. Eventually, one particularly enlightened Tiver (whose name is unpronounceable with human sounds, but would something along the lines of "Mathew") stated that the senseless violence must stop, and that amends must be made between the species. Soon, all were united-except the Xurlans, who abstained from the unification and they became the United Sentient Republic.