When a Kymellian called Aelfyre Whitemane gave Power Pack their powers, he also gave them Friday, a 'smartship' which is practically alive, makes its own decisions and has feelings.
Friday has many weapons, can adapt to any environment and can gain warp speed travel. Even though Friday could, in a way think for her self, she was still programmed to do what the Kymellians told her do. This changed after she crash landed and "died". Many attempts where made to repair her, but none of them worked. It was not until Power Pack came to see her that she healed. After that, she went with Power Pack to earth, deliberately disobeying the Kymellian's orders. It was, however, extremely useful when she came to Earth with the Pack as she was able to help them defeat the Snarks.
During the Secret Invasion Friday helped the Pack and Franklin Richards to defeat attempts by the Super-Skrull to steal a map that would lead him to a great power. Friday really proved herself in this battle and the fact that she doesn't acknowledge H.E.R.B.I.E at all.
Friday is extremely sarcastic. She is also the love interest of H.E.R.B.I.E, but doesn't even know he exists. Over the course of the newer Power Pack series, starting with Day One, Friday has become more and more human like in her speech patterns and decision making.