Of course Cas wouldn't know anyone by their codenames, "I'll ask Dick.. next time I see him." He knew the oldest Robin worked in Medical, hopefully Sam would get a chance to catch him on his rounds or whatever. It was highly unlikely he'd be checking his tablet anytime soon, he couldn't concentrate enough.
The matter of fact response from the angel had Sam laughing softly, trying not to agitate his wound, and he shifted slightly, wanting to sit up more. As if Castiel had read his mind, his friend leaned over and helped raise the bed. Sam managed not to wince, much and gladly took the offered water. "Thanks."
Noting how Castiel dodged his question, Sam allowed him a moment's grace before he raised his eyebrows, hoping the look would be enough to encourage the seraph to speak. Arriving on Knowhere threw everyone for a loop, but arriving in the midst of a battle must have been even more disorientating. Or apparently not, "fine, huh? Glad you're okay."
"Cas, did I grow an extra head, or have I got something on my face?" Sam asked with a little smile, "you're staring, a little. I can't look that different to how you and Dean remember."