Shes paired with every possible character (and more than a few impossible), both in Buffy and Angel and in other shows as well, and has taken on all manner of big bads to save the day.
However, she is also one of the more difficult characters to write well.
Buffy is one of the longest-lived Slayers, and has returned from death not once, but twice, an act that disrupted the magic surrounding the traditional Slayer line.
During their war with the First Evil, Buffy enacted a plan to activate every Potential Slayers in the world, abolishing the traditional line of "Chosen Ones," before dedicating herself to gathering and training the Slayers she was responsible for creating.
Her mother was supercilious and distant, noticing Willow had cut her hair months after she actually had it cut.Willow was introduced to the forces of magic by attempting a complex spell to re-ensoul Angel.To her own surprise, Willow tapped into considerable power during this ritual, and would come to practice witchcraft.A few years after the destruction of Sunnydale, Buffy, along with Angel, was involved in an ancient prophecy that would bring about the sentient "Twilight" dimension, destroying the Earth in the process.When Angel, possessed by Twilight, murdered her beloved Watcher and father figure, Rupert Giles, Buffy, enraged and grief-stricken, destroyed the Seed of Wonder, thus bringing about the end of magic on Earth.Willow was quick to grasp basic spells and with support from her girlfriend Tara Maclay, her powers blossomed even more rapidly as did her self-confidence.