"Stop pretending, Leafpaw. To me, StarClan, our warrior ancestors, these signs we're supposed to interpret--they're nothing but a bunch of stories to keep the Clans happy."—Mothwing admitting she doesn't believe in StarClan in Starlight, page 248
RiverClan, Loner (formerly)
She was was unhappy that her father was Tigerstar, because of his background.
Mothpaw was different from her brothers. Hawkpaw always wanted to be a warrior but not Mothpaw. She wanted to be a medicine cat. Her mentor was Mudfur. He was a great medicine cat, and a great mentor. She wasn't forest-born, so she had to prove herself.
She was worried that her Clan would not let her be a medicine cat, but when it was drawing close to the day the medicine cats got together, she was chosen.
When Mudfur died, she was made a medicine cat before she was ready, and was named Mothwing. When the cats were on a journey, she had to heal lots of sick cats.
Soon after the journey, her friend Leafpaw became Leafpool because she discovered Moonpool, but Mothwing never used Moonpool because she did not believe in StarClan. She got an apprentice named Willowpaw, who later became Willowshine. She is still alive in RiverClan.