The side of Rei’s face, somewhat
top-down view. She raises her head and speaks
REI:“—I'll protect you.”
Kendrix: Her usual expression changes to a slightly determined one as she tilts her head up. She wasn't really trying to comfort him here, but, from her perspective, simply reminding him of the plan, but if you see it from Shinji's perspective and take into consideration how he must've been feeling at the time, Rei happened to pick just the right words.
He also reacts shocked/surprised at the first part of the statement in 190.