Ingrid Hannigan

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

Ingrid Hunnigan was Leon S. Kennedy's only US Secret Service 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 marines upon confirmation that the t-virus was responsible of the outbreak.

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.