Making a Mousefolk 

• Ability Score Increase. Your Dexterity score increases by 2.
• Age. Mousefolk mature in their teens and live around 80 years.
• Alignment. Most mousefolk are neutral good. They tend to be kind-hearted and have deeply-rooted values.
• Size. Mousefolk are among the smallest of Aghera's races, typically standing no taller than 3 feet and weighing no more than 40 pounds. Your size is Small. 
• Speed. Your base walking speed is 25 feet.
• Darkvision. You can see in dim light within 60 feet of you as if it was bright light, and darkness as if it it was dim light. You can't discern color in darkness, only shades of grey. 
• Lightfooted. You have proficiency in the Stealth skill.
• Scurry. You can move through the space of any hostile creature as if it were difficult terrain.
• Squeeze. You suffer no penalty for squeezing into a space that is only large enough for a creature that is one size smaller than you.
• Languages. You can speak, read, and write Common. You can also speak Rodentia, a quiet and squeaky language that has no established written form. 
• Subrace. Mousefolk are commonly divided into two subraces: mouselings and ratlings. Choose one of these subraces. 

Mouseling

Mouselings are smaller than their ratling cousins, but are all the more daring. They sport a variety of coats, from grey to brown to very rare whites, but all possess large ears and round, dark eyes. 

• Ability Score Increase. Your Charisma score increases by 1.
• Brave. You have advantage on saving throws you make against being Frightened. 
• Nimble Escape. When a creature you can see makes an opportunity attack against you, you can use your reaction to impose disadvantage on the attack roll. You can't use this trait when wearing medium or heavy armor.

Ratling

Ratlings often stand a full foot taller than their mouseling relatives, with longer tails and more pointed ears. They are tougher, more resistant to poison, and far more stubborn than other mousefolk, but are unquestionably resourceful. When needed, a ratling can escape just about any enclosure that isn't constructed entirely from metal and stone, a fact that many jailers hold in contempt.

• Ability Score Increase. Your Strength or Constitution score increases by 1. 
• Gnaw. You can use your action to chew through and break a small nonmagical object that isn't being worn or carried, like a rope, wooden rod, or handle. If you chew on a wooden wall or floor for 1 minute, you can know a hole large enough for a Tiny creature. You can't chew through materials that are harder than your teeth, such as metal, stone, or crystals. 
• Bite. Your fanged maw is a natural weapon, which you can use to make unarmed strikes. If you hit with it, you deal piercing damage equal to 1d4 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike.
• Rat Resilience. You have advantage on saving throws against poison, and you have resistance against poison damage.