Syrinx was an attentive listener watching the way Castor's lips move, his expressions, she was unsure on how much patience he would have with her- after all no words. Her own words could be read in the smiles, the way her eyes would dart behind him- expecting something(one) to interrupt. Her fingers clasping and fiddling, lips pressed in a thin-line or slightly parted.
She offered a hesitant smile at his first confession- not quite trusting it, but accepting it nevertheless. At the question she shook her head quickly, sending hair spilling over messily in a childish manner. If it got too loud that was alright- Syrinx tapped her lips and gestured to his own. Lip-reading she could do.
It was difficult but she tried- gesturing and smiling to convey that she had not expected to meet him any time soon.