Rebecca Gillies is probably Mark Darcy's administrative assistant or junior legal partner; it is never really made clear exactly what her role is, but she accompanies him a lot professionally and attends the same social functions as Mark, a well-known human rights barrister. On-screen dialog indicates she is 22 (which is unlikely) and her father owns half of Australia, thereby wealthy -- how she came to be working for a lawyer in the UK is never really explained.It is presumed throughout the movie (which is mostly in Bridget Jones's POV) that Rebecca is out to get Mark for herself (after all, she certainly is in the book, from which this diverges incredibly). She does appear to spend a lot of time with Mark, and is exceedingly nice to Bridget, which makes Bridget suspicious. It is accusations of infidelity, Bridget accusing Mark of having an affair with Rebecca, that drive Bridget and Mark apart. In the end, however, it is made clear that Rebecca has spent all of this time in Mark's company not to be close to Mark, but to be close to Bridget, revealed when Rebecca confesses her love for Bridget and kisses her, inadvertently clearing Mark of all wrongdoing and paving the way for Mark and Bridget to become engaged. Show less «