Sydney Bristow is the main character of the TV series "Alias." She is played by Jennifer Garner and is a highly skilled agent working for the CIA's black-ops division. Sydney is portrayed as a strong and intelligent woman who is capable of handling difficult situations, both physically and mentally.

Sydney is initially recruited by a criminal organization called SD-6, which she believes is a legitimate government agency. However, she soon discovers the truth and becomes a double agent, working to bring down the organization from the inside. Sydney is determined to bring justice to those who have been wronged by SD-6 and to protect innocent people from its harmful operations.

Throughout the series, Sydney goes through a lot of personal turmoil, including the loss of her fiance, the discovery of her mother's past, and the difficulties of keeping her secret life hidden from her friends and family. Despite all these challenges, she remains committed to her mission and to the people she cares about.

Sydney is also known for her physical abilities, including martial arts and acrobatics. She is often seen going on dangerous missions, where she uses her skills and knowledge to complete her objectives.

Overall, Sydney Bristow is a complex and multifaceted character who embodies strength, resilience, and determination. She is one of the main reasons "Alias" became such a popular and successful series.