Twelve bears no active personality, usually copying its opponents' quips and uttering "target" and "complete". Beyond this, Twelve is only capable of expressing itself in a binary code cypher (00001 = A, 00010 = B, etc.). Its winquotes imply a simplistic, aggressive and even thuggish personality, akin to that of an arrogant foot soldier.

In its rival battle against Necro however, Twelve is shown speaking in a normal manner. Twelve isn't without quirks in its personality, however.