Homebrew
Mouselings are smaller than their ratling cousins but all the more daring. They sport a wide variety of coats, from grey to brown to very rare whites, but all possess large ears and round, black eyes. Though these features often make them look adorable to big folk, most mouselings want nothing more than to be taken seriously. They fancy themselves knights, merchants, minstrels, explorers, and a wide variety of other occupations; only humans rival mouselings for ambition.
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.