Penelope was a banded Brightwing who was banished by her colony before Marina.
Penelope in hte TV series

Penelope in the TV series

Marina and Shade find her and the other banded bats during a blizzard. Their leader was Scirocco. Penelope and some of the other banded bats get away after Shade and Marina warned them about Goth and Throbb. She then pointed Shade and Marina in the right direction towards Wolf's Ears. Penelope might have taken leadership of the new colony of banded bats and became their elder. In the book, however, it is unknown whether or not she was among those who escaped from Goth and Throbb or not.