Two and all the other even numbers have flat tops when they stand two blocks wide, as demonstrated in Odds and Evens. He is very kind and is also One's best friend.

One is very extroverted, sweet, curious, helpful, bubbly, friendly, and childish. She loves finding singular things and normally calls them "one of something", while the other Numberblocks would usually call a singular thing "a something" (e.g. One would call a single bee “one bee” while the other Numberblocks would call it “a bee”). "Two is male"