Lockette is the Pixie of Portals (Pixie of Direction in the Nickelodeon dub), thus knowing her way anywhere. She has a hair clip that transforms into a scepter which helps her point people in the right direction.
Bloom often finds herself lost and is constantly on a journey to discover the secrets of her past throughout the series (Or 'has many hidden passages in her heart'). Lockette not only helps Bloom find her way physically, but also emotionally, as Bloom tries to discover her true self and connect with her power and family. Some people believe that Lockette might also have the power to open magical portals to other worlds. She is Bloom's bonded pixie.
Being the second youngest of the Winx' pixies after Piff, her feelings get hurt easily.
In Season 3, she seems to have a dislike for Sky due to the brainwashing incident but she forgives him (but still becomes protective of Bloom). She also helps Bloom through all her emotional turmoil in Season 3.