Why does cloudpaw go to twolegs?

Cloudpaw, after becoming Fireheart's apprentice, proves to be extremely stubborn and selfish, and later betrays the warrior code by allowing Twolegs to feed him. Later, he learns his lesson when he is captured by the Twolegs and stolen from the forest. Fireheart, Sandstorm, and Ravenpaw rescue him, and he proves to be a diligent, hardworking apprentice from then on. Bluestar makes him a warrior, Cloudtail. Later on, he becomes the mate of Brightheart and has one kit with her, Whitewing.