Dr. Brainiac a.k.a. Linus
Sometimes you need a smart cat around. Linus is one of the best cat brains out there, and a fine companion to bring on patrols.
Science Cat
Linus is a smart and wise cat. Some of this wisdom come from his long life experience, but even when he was younger he was above the rest of his litter in intelligence. It helps that he has a calm demeanor and shows an almost unnatural patience for a cat.
As a scientist, it helps having a spirit of exploration. Linus is the cat who will hitch a ride with the transportation devices of humans to get to see new places, sometimes with no plan on how to get back. However, it has worked out every time he has done this, as his humans will always track him down in one way or another. Needless to say, he shows no signs of stopping this behavior.
A Diplomat
With his calm demeanor and seemingly neverending patience, Linus is often used as a diplomat in more difficult cases, both involving other cats and humans.
His skills as an intercat diplomat is proven as he's the only cat who has accepted Hugo the Overlord right away, despite the leader's inability to speak cat at times. Linus' calm demeanor stopped him from swatting Hugo in the face the second they met, despite the other running directly at him. If this doesn't convince you of his diplomatic skills, nothing will.
The humans know Linus as a friendly fellow with a low, croaky meow, always walking over to greet the people he know. He's generally easygoing, but if he gets locked up inside alone for too long he's not afraid to show his displeasure by leaving a gift on the floor.
Linguistic Skills
Another proof of Linus' intelligence is that he understands human speech. There were a few times when Hugo's humans asked him to find the Overlord, and if this happened when Linus didn't have any Important Cat Business to attend to, he would start the search for his friend. The humans' faces were priceless when the Overlord returned within ten minutes after Linus left. Another sign that the humans underestimate us, of course.
However, as Linus is a cat, he can't show that he understands the human language too often. If you start making the humans know too much of our skills, they will start to suspect other things, and the whole ICB might be in danger.
Diplomat (Intercat and cat to human)
A cat. A Scientist. What's more to like? The best of both worlds with zero downsides. I love it :D