Twenty-One, or 21, is a Numberblock that is made of 21 blocks. Twenty-One is friendly, curious, and adventurous. Twenty-One loves to explore numbers and is great at helping new Numberblocks figure themselves out.
There are roughly one-sh*t billion tropes so PLEASE look through them before adding one. Otherwise add what you like. ADDITION: PLEASE read through the trope description provided before submitting something. It's not a huge deal but too often people submit characters that don't fit just because they misinterpreted the title...
