Physical Desc.
Slugcats are literally liquid, being the result of purposeful breeding and experimentation by the Ancients in order to make the perfect creature for cleaning out sewers. They are able to store things in their stomachs to be discarded later, but usually just use this unique ability to store items of value. They come in a wide variety of colors and are able to evolve odd traits for survival relatively quickly. They have the tails, legs, and ears of a cat, but walk and run on two legs. In addition, they are quite adept climbers because of their ability to rapidly shift their masses to reach advantageous handholds.

History
Since the Ancients disappeared, slugcats have taken over the sewers of the world, breeding like rabbits and establishing colonies. They have been given Marks of Communication by another race, and have since shared them amongst themselves to learn Common. Because of their small and weak nature, slugcats that go out on their own for large periods usually don't last long. They have a rocky relationship with scavengers, with individual colonies varying in how they treat them. Typically, slugcats are quite skittish, fleeing from anything that might be considered a threat.

Society
Slugcat colonies have many roles that its members play, all in the interest of preserving the colony. Slugcats are often willing to risk their own lives to save their family and colony members and have very close bonds with each other. Most slugcats are simply foragers, gathering food amongst the ruins of the Ancients. Others hunt for more challenging prey, which yields a more plentiful bounty at the cost of greater risk. Every colony has at least one scout that patrols the colony's territory and alerts it of any threats. Depending on their location, some have a form of diplomat to trade information and tools with scavengers. Other, more specialized roles are also found, but these are the most common. In addition, most colonies have a leader, a slugcat who guides them through exceedingly oppressive rains or through scavenger raids. These leaders are often more adept at combating the world's threats than the average slugcat, or even some of the hunters. If a slugcat is found out in the wild, it will always be taken in and cared for, with the expectation that it will be returned to its own colony or, if it has none, contribute to its newfound colony.

Slugcat Traits

Ability Score Increase

Your Dexterity score increases by 2.

Amorphous

You can squeeze through a space as narrow as 1 inch wide. You also have advantage on ability checks you make to initiate or escape a grappled.

Karmic Aptitude

When you finish a long rest, gain temporary hit points equal to your proficiency bonus. If you were reduced to 0 hit points between your last long rest and this one, do not gain any temporary hit points.

Stomach of Storage

As an action, you may swallow an object to place it in a cavity in your belly adjacent to your stomach. This object must be able to fit in your mouth, like a gem or a pocket knife, and the total weight of things in your secondary stomach cannot exceed 2 pounds or 6 cubic inches. As an action, you can retrieve any or all objects you have stored. You can't store living things in your storage stomach; you instead just eat them like a normal slugcat.

Languages

You can speak, read, and write Common.