Rats
Ability Score Modifiers: Rats are a famously diverse and adaptable species. They gain +2 to any ability score of their choice.
Type: Rats are humaniods with the rodent subtype.
Size: Medium.
Speed: 30ft, Burrow 5ft, Climb 20ft.
Skills: Rats gain a +2 bonus on Survival and Knowledge(Local) checks.
Low-Light Vision
Scavenger: Rats receive a +2 racial bonus on Appraise checks and on Perception checks to find hidden objects(such as traps or secret doors), determine whether food is spoiled, or identify a potion by taste.
Weapon Familiarity: Rats are proficient with cutlasses and tailblades.
Alternate Racial Traits
Fancy Rat: More domestic rats have more vibrate pelts than their wilder brethren. They gain a +2 bonus on Diplomacy and Knowledge(Nobility) checks. This alters Skills.
Sea Rat: Some rats are drawn to the sea. They gain a Swim speed of 10ft. This replaces your Burrow Speed.
Corsair: Rats often have a not undeserved reputation for piracy. They gain a Swim speed of 10ft, proficiency with 2 of the following: Boarding Axe, Boarding Gaff, Boarding Pike, Cat'o'Nine Tails, Cutlass, Grappling Hook, Harpoon, and Sea Knife. This replaces Scavenger and Burrow speed.
Tree Rat: Some rats are born to to climb. Their climb speed increases to 30ft. This replaces Burrow speed.
Scourge: A rare few rats have tails that are longer and stronger than most. They gain a Tail Slap & Trip attack. This replaces Scavenger and Low-light vision.
Favored Class Bonus
Alchemist: Add 1 extract formula to the alchemist's formula book. This must be at least 1 level below the highest formula level you can create.
Fighter: Add +2 bonus on rolls to stabilize when dying.
Paladin: Add +1/2 hit points to the Lay on Hands ability.
Rouge: Add +1 foot to the maximum range you can Sneak Attack.