Many games these days seem to leave you alone. Not in that the game acts like an absent parent, but in that it mainly consists only of your player and the hordes of enemies you blast away with psychopathic glee. Granted, some give you other "characters" to talk to, complete with twitchy facial animations and strange, unrecognizable accents. But, whether it's Halo, Half Life 1, or Bioshock, you are alone for most of the game, with nothing but your shotgun for company (don't be getting any nasty ideas, you).
And you know what? In most of these games, I kind of like it that way. Let's be perfectly honest: most game companies nowadays, with the exception of a few like Bioware or Infinity Ward, can't write worth crap. And if you can't write, please-o-please-o-please-o-please, don't. Just leave me alone and give me guys to shoot.
That is one of my favorite things about pets in games. They're characters in their own rights, but they play to many game developers' strengths; they don't talk. Ironically, many of the developers who use pets, like Black Isle, Bioware, or Lionhead, are the ones who can write, so that point kind of goes out the window.
I'm not saying that pets are the easy way out. Dear God, I'm not. Like I said before, good pets in games are characters in their own rights, but their characters have to be built without what is normally both the brick and the mortar in traditional character development: dialog.
This is like trying to build a house without being able to use a ladder: you can build the foundation pretty easily (slap some big eyes on that sucker), but building anything higher is going to take something else all too many game developers have all too little of: finesse.
It's the little things that make pets in games great. The first time you come back after getting a snack to find your dog peeing on your character's leg, or when they jump into bed next to your character, it's these "Aww" or "Eww" moments that really strengthen your tie to your pet. In Shadow of the Colossus, I still smile when I press X, hear my character call, "Argo!", and see that black horse gallop up over the hill towards me.
Speaking of SotC, another thing that pets are great for is preserving the feeling of solitude in a game while still giving you something other that your own character to latch onto. While prowling the plains of that game, the only thing other than you is Argo, some lizards, maybe a bird or two, and, of course, the Colossi. If it was just you, that game would very quickly get oppressively lonely. It's still lonely even with Argo, but not oppressively so.
And, of course, (Spoiler!) pets can provide great feelings of sadness when you lose them. Definatly one of the saddest moments in a game that I can remember is when Argo launches the main character of SotC off of his back to save him from the crumbling bridge that the horse is racing across. Argo then falls into the chasm below, with the main character, looking down from the ledge that Argo propelled him to, giving one last "Argo!" as he falls.
The fact that I still remember that scene so vividly above any other is a testament to the power of the pet. In Mass Effect, I felt a little guilt about leaving Kaiden to die in order to save Ashley, but that sacrifice, by a human, just doesn't compare to that of a pet to save its master. For whatever reason, that's the way most humans work, and the smart developers turn that to their advantage.
So, in conclusion, Including a pet in a game where the player is otherwise solitary for the most part can add an interesting dynamic to the game. They can make you feel things that are hard to achieve with a human character, while presenting their own challenges. Characters don't need to be alone in order to be badasses. After all, don't you think that deep in his heart, all Master Chief really wants is a little kitty?
