Although you can play the game solo (which becomes increasingly difficult as you forge ahead), you can hire party members of various kinds to aid you along the way. All of them have different pros and cons and their alignment also affects your partnership. Some of them are friendly and loyal, others not so much. It's up to you how you solve this problem. if you adventure together long enough, you can even fall in love with one of them, but this has some conditions, so it's not trivial.
There is an enormous amount of companion banter in the game, either in conversations with other NPCs or between you and him/her. This gives you a greater insight into their personalities, adds lots of flavor, humor and thought-provoking ideas. As you progress, it is very pssible that your and their alignment will change for the better or worse. This will affect some decisions and equipment usage. Some of the party members outright hate each other.
Due to the extremely non-linear nature of the game, it is possible that you can't find all of the possible companions or even if you can, they refuse to join for some reason. If you have more than your party can hold, It is a good practice to park them and use their skills eventually when you can't get through a particular obstacle. your journal will record where they have been left behind so that you can find them more easily.