To the point, what Pluto truly is, is a well trained dog. Like his master Mickey he can get into a large amount of trouble but has enough brains to escape the situation. He acts as Mickey's sidekick, best friend, conscience in some occasions and pet. The pup is extremely loyal but on occasion does have the tendency to argue and be fussy with people or even Mickey.
He shows a strong disliking towards cats. This hatred could have mostly been sparked but not only natural instincts, but the rivalry with Minnie's cat Figaro. The two constantly compete for Minnie's attention and love but in recent years have been much kinder to each other.
While intelligent enough, Pluto can be a bit clumsy and his childlike persona is often mistaken for stupidity. He's not immune to being outwitted but can get back on track which is usually bad news being that Pluto can have a nasty temper. He has two consciences. One evil (which is Pluto's devil counterpart) and one good (which is Pluto's angel counterpart). They occasional appear in hard situations and Pluto tends to listen to the negative side at the beginning but the positive does not take no for an answer having Pluto do good in the end.
The pup has an a-list life. A good home, family, and the greatest owner for his type but he has been accidentally mistreated. Being that he spends most time in the house, he has been blamed for a handful of things. His pal Mickey has always forgave in the end as he is often reminded why Pluto is deemed his best friend.