Ingrid Hannigan

May I remind you that you're still on duty.

Ingrid Hunnigan was Leon S. Kennedy's only Department of Security Operations link during his mission to rescue Ashley Graham.

Los Ganados Incident
She occasionally contacted him to ask how he was coming along or to give information. When he entered Ramon Salazar's castle, he was unfortunately out of contact with her for several hours because Los Illuminados hijacked their communications line. He couldn't regain the line until the Island, which housed the hijacking equipment, blew up.

Earlier in the game, Leon talks to Ingrid about halfway through when their frequency is hijacked. At the start of the game, she has glasses on. When Leon finally gets back in contact with her, she is without glasses, prompting Leon to flirt with her, leading her to reject his advances and to remind him that he's still on duty. However, she smiled when he flirted with her, and had a subtle smirk on her face when reprimanding him.

Harvardville Airport Incident
Hunnigan assisted Leon again during the Harvardville Outbreak, where she had the President send in elements of the United States Marine Corps, who were vaccinated against the t-Virus upon confirmation that it was responsible for the outbreak.

Tall Oaks Outbreak
She is helping Leon by giving him information of the outbreak. She appears to be helping Leon in secret due to him being blamed for killing the President, because she believes he is not responsible for the President's death.

Trivia

 * Despite not being a playable character herself, in Resident Evil 5: Gold Edition (and PC version), an outfit entitled "Business" which is only available for Sheva Alomar bears a strong resemblance to Hunnigan.
 * Claire's alternate costume in Mercenaries 3D resembles Hunnigan's clothes.
 * Ingrid Hunnigan will make an appearance on Resident Evil 6, according to the recent trailer. She is seen updating Leon Kennedy on the status of the outbreak.
 * In Darkside Chronicles, in the Communication from Krauser voice files, Krauser's mission support ally introduces herself as "Ingrid Hannah," though it is not certain if it is meant to be Hunnigan using a pseudonym, a naming error or someone else altogether.