How to obtain a pet

[ILLEST]

I tried searching online and in these forums but i can not get a clear answer also because the game did not come with a physical booklet.

What i need to know is can any class get a pet or do you need to be a certain class?
If any class can get one where do you get them and which is the easiest to get?

I bought this game as an impulse buy while i was in gamestop yesterday so any help will be appreciated thank you