The fact that Claire broke into an Umbrella base to find her brother, and then continued to search for him even after being captured in Code Veronica. And the fact that the moment he heard she was in danger Chris instantly sprung into action, climbed up the rock face of the island and then flew a plane to Antartica to find Claire in return.
Claire comforting Steve after his father died. Also when she assured him they would escape together and didn't blame him for the mistake he made in moving the drill and releasing the gas.
Rodrigo starts off as another mook who was responsible for capturing Claire Redfield. Then he realizes the error of his ways and frees her. Despite his gruff demeanor, he clearly cares about her and would probably have helped her escape if he weren't so badly injured. One of the most heartwarming moments in the game is the optional cutscene in which Claire returns to give him hemostatic medicine which makes his last hours a little more comfortable. She also gives him her lighter which holds sentimental value because Chris gave it to her. It would be worth it to help him even if he didn't give you a lockpick which allows you to ultimately turn your Beretta 93R into a Disc One Nuke