Finally we arrive at the post for the fifth rattie, the smallest but not the least, Cao Cao. Cao Cao was the first named, along with Lu Bu, for he was a mighty rat even though he was also really really small, with Lu Bu weighing in at nearly 50% more. He's still the smallest rat, but he's also the most active one as well.
We got a nifty rat wheel, featured in this picture:

It's an enclosed wheel, with the openings on the opposite side from that seen in this picture. Playing nearby are Blue and Scotty, with Lu Bu watching. All new things you introduce the ratties to naturally brings a certain amount of skepticism from them, which usually means that eagerly waiting to see how they will interact with a new thing usually brings disappointment as they ignore it. Cao Cao, however, figured out right away exactly what the rat wheel was for and immediately ran like crazy in it. And ran like crazy when we were trying to get to sleep, and then taught the rest of them how to run like crazy on it so that they could continue running while we tried to sleep even after Cao Cao got tired.
Here we have a good picture of Cao Cao:

He's a siamese coloring, which is basically a pure white with grey-brown hints on the ears, nose and tail. He's also the only one with the red eyes, the rest having the more usual black eyes.
To round out this description of Cao Cao and his personality, we have a photographic sequence, which I'll just notate with various bits about him. (Does anyone know how to make stuff on blogger appear only after a link? "below the fold" as it's usually called. I'd like to do that with the extra pictures here so it doesn't get too weighty.)
Cao Cao is a natural acrobat:

Yep, that's a three feet on the cage, one foot on the clothes hamper, getting set to jump over.

If you start taking pictures of rats, they come to see what all the flash is about.

But sometimes they get distracted and instead show off their balancing skills.
The next sequence shows off a particular trait we've seen in the ratties: they get into trouble. For some background, L went to a huge amount of trouble to buy some really nice cable organizers to stow all the power cables, network cables, etc, to keep them out of the way of the rats (who like to chew), so that we could at times let them run around the bedroom. Naturally, this doesn't work terribly well, as evidenced by the following behavior:

"Who, me? Play on the neatly organized cables?"

"Ok, enough posing for the camera. Now, what can I do while I'm up here?"

"I wonder where this cable goes?"

"This looks promising." (This is actually how he got over there, that black cable his front paws are resting on is the power cord from one of my monitors, he climbed over on top of it.)

"Changed my mind, it's climbing time again!"

"You know, this place looks pretty familiar. Where should I go from here?"
He actually did several loops around like that and then used the power cord to climb back over to the desk. I think he just likes the climbing around. Of course, once he arrived on the desk, this is what happens next:

After an exhausting trip, he naturally had to have a Dr. Pepper. I'm just glad he didn't try to drag it off with him. There you have it: Cao Cao, adventure-rat.