Clear
Lightning
Name: Claire "Lightning" Farron
Japanese name: ライトニング (エクレール・ファロン)
Age: 21
Occupation: Former sergeant in the Guardian Corps, Bodhum Security Regiment
Hometown: Bodhum
Height: 5'7" (1.71m)
Weapon: Gunblade
Seiyuu: Maaya Sakamoto
Voice actor: Ali Hillis
Lightning lost her father at a young age and her mother when she was fifteen. With a younger sister, Serah, to care for, Lightning had to grow up quickly. She decided to abandon her given name, "Claire," and take on the name "Lightning" as a symbol of the strength she wanted to portray for her younger sister.
Following her graduation from high school, Lightning joined the local Guardian Corps regiment in her hometown, Bodhum, and worked there to make ends meet. She soon became a workaholic, however, and her goal of working to provide for her sister overcame the desire to spend time with her. This was something Lightning had just come to realize in the days before the start of the game, as detailed in the prequel novella.
As shown in the game, Lightning initially rejects the idea that Serah could have become a l'Cie, but soon realizes she was telling the truth. Lightning quits her job and voluntarily boards a Purge train in order to go after Serah in hopes of saving her, but Lightning ends up becoming a l'Cie herself.
Lightning is introduced at the worst possible point in her life, and the first few chapters of the game are crucial for her character development. While she starts out as cold, single-minded, cynical, and pragmatic above all else, she gradually learns how to hope again and how to open her heart and care.
Gameplay
Lightning's default roles are Commando, Ravager, and Medic. She's equally viable as a Commando and Ravager, and isn't the best in the group at either. In essence, she's an all-rounder; you'll frequently want to flip between Commando and Ravager as the situation demands it. Lightning is a passable Medic, but there's really no situation where you'd ever want her as your main healer given that her best healing spell is Cura. She's your second healer in a Combat Clinic paradigm, no more.
I usually run with Lightning as my party leader in a Lightning/Fang/Hope party, since her Full ATB Skill, Army of One, is great at raising the stagger gauge. However, in post-game play, her other roles can be useful in other party configurations; she's an excellent Synergist. You can find her full crystarium here.
Her Eidolon is Odin; I don't find it terribly useful, but your mileage may vary. I tend to go with Lionheart as the base for her Omega Weapon for its Quick Stagger property.