FINALLY SOMEWHERE I CAN POST ABOUT THIS OMG YES
I recently watched some Tom and Jerry cartoons, and I was appalled at how much of a jerk Jerry is to Tom. In the majority of episodes, it was Jerry who first gained Tom's ire, but there were some in which Tom was first to cause trouble.
Their relationship is best described as love-hate. They love to chase and be chased, hurt and be hurt. In one episode, Jerry finds his current life boring, and leaves a note for Tom while he sleeps that he is heading to the big city. Once he gets there, he realizes that city life is too hectic and crazy and he rushes back home and rips up the note, planting a big wet one on a sleeping Tom, who wakes up thoroughly confused.
Tom has also showed that despite their differences, Jerry is extremely important to him, quite possibly the most important figure in his life. He has captured Jerry numerous times, and not once has he truly been able to kill him, as it would be tremendously easy to simply bite off Jerry's head and kill him.
He relies on Jerry to bring excitement into his life. In one episode, after much fighting, Jerry gets fed up and storms out, ignoring Tom's scares. When Tom realizes what he's done, he freaks out, offering Jerry numerous methods with which to cause him harm, and Jerry refuses them all and simply walks out the door.
Whether or not either of them can be described as "the bad guy" based solely on their behavior is pretty much impossible. Both of them are two halves of the same whole. Without one, the other would clearly go insane, which is why Tom won't actually kill Jerry despite having numerous chances to (he actually saved Jerry from freezing to death in one episode), and why Jerry doesn't move out of the house Tom is in and go live with Spike, who would gladly let him stay.
Spike seems to go after Tom solely because he is chasing Jerry, not because he's a cat. He can't really be seen as the bad guy, either, because Spike simply thinks he is protecting his friend by pummeling Tom. Tom, on the other hand, is terrified of Spike because he is an enormous, ferocious dog, so he doesn't ask questions when Spike lays into him. He expects it.
To summarize, Tom and Jerry is a cartoon with two villains and no villains. Each has done something to fan the flames of war - and they wouldn't have it any other way.