Introduced in Season 2 The Conversation, she works in the District Attorney's office.
She met Zajac when he requested charges be dropped for homeowners trying to protect their foreclosed homes from being occupied by Lennox Gardens displaced residents. She enjoyed bantering with Zajac ("If a politician pulls a stunt and it doesn't hit the front page, does he even make a sound!") Claire met him at a bar later to tell him the charges were dropped and to apologize for arguing saying she likes winning; then they slept together.
In Consequences, her boss, Jim Doyle, directed her to sexually satisfy herself while he watched in his office. He had also directed her to influence Zajac, but didn't specify to get sexually involved.