Russia is a civilization old and great enough to understand that China will eventually surpass the US to become the strongest power on planet earth. And the last thing you want to do is be enemy with it when it is still young.

Also, both Russia and China are smart enough to understand they are too strong and too close to be enemies, it would be disastrous for both sides. They are "friends" because they have to be friends.

And what do you think the US would do after China surpasses it? Continue to mess up with China? No, it would make a 180 turn and try to make ally with China. And Russia knows that so it has to be ally with China before the US does.

As for China, all it wants is "peaceful development" because time is on its side. Thus, it wants to be a "friend" with all global powers including the US. Although we should worry about what it would do after it surpasses the US, but for now, we can't really blame it for trying to develop its economy or blame its people for trying to improve their life.