[Fai smiles brighter, partially because Syaoran's concern is touching and partially to reassure the boy, and reaches up to pat Syaoran's cheek affectionately.]
That's very sweet of you to ask, but you don't need to worry about me. I'm just fine! And now that you're here, things will be even better. Who knows, maybe we'll even find the others!
[There's some genuine hope behind his words, even if it's not quite as much as he's letting on. Still, finding Syaoran is a good start. It's... possible, at least.]