Ratchet

Ratchet is about 4'9", he's an orange and yellow Lombax. In Ratchet & Clank, Ratchet was voiced by Mikey Kelley. From Going Commando on, he is voiced by James Arnold Taylor.

Attitude
Ratchet's your typical teenage guy: cocky, smart-mouthed, and full of himself. You either love 'im or hate 'im. He's something of a mechanic/inventor; he built the ship that starts the whole adventure. Of course, he promptly wrecked it on the next planet. Nothing is said, to my knowledge, of his family or any other Lombax living on Veldin. Most of his humor is very sarcastic, sometimes downright mean. Especially when he gets mad at somebody. Then he holds a nasty grudge. Revenge, of course, is sweet.

Ratchet & Clank
At first, he only agrees to go along with Clank because it's a way to get off his little backwater planet. Later on, he actually agrees to save the galaxy because Drek's "just plain mean".

Going Commando
Ratchet is slightly more "mature" and not half so mean, but also a bit more gullible. It's also been suggested that he has something going for a certain female, (Angela Cross) though no concrete evidence is ever provided; just little hints and tips scattered over the game.

Up Your Arsenal
However, nothing lasting apparently comes of any sort of relationship he may have had, as Angela only make a return in Up Your Arsenal as a cameo at the end. Ratchet's got other interests, it seems (or rather, others are interested in him. He's a bit shy and awkward around girls).