Stanford Pines has been exploring the multiverse for about 10 years now, He entered when he was accidentally pushed in by his brother through a portal, the multiverse is extremely dangerous, and he needs to be cautious at all times.
Stanford Pines is defensive of his safety, he is incredibly smart and a very well gifted explorer. He has six fingers, an extreme abnormality and he's as cautious as he can be. 
He's smart, and not want to take risks. Although he does have a soft caring side.