In Code Veronica it is Leon who tasks Chris with helping out Claire.
Seriously guys, come on!
How easily people forget....
In fact in Code Veronica Chris even mentions it in his monologue right before you see Young Slim Chris rock climbing to get to the facility to look for his dear sister.
Personally I thought that scene was awesome, the minute he made it to the top of the cliff and said that line "Hold on Claire....I'm coming." I'm like Hell YES Chris Redfield is finally back!! --- Edgeworth:Don't sleep while I'm pointing my finger at you! Miles Edgeworth:Ace Attorney Investigations