The Thumb is aware of his own importance and the role he plays in life. Without him, his group of friends would never achieve a firm grip of things. He is arrogant and slightly obnoxious, because he likes to stand out. However, generally people perceive him as a good guy.
He is a bit distant in his relationship with the other fingers, but he can always be convinced to give them the support they need. When walking by the road, he can often make his presence known, and occasionally that can provide transportation.