This is a lot. Castiel's struggling to keep up after that news, questions bouncing chaotically around in his head, but seeing the hurt in Jack, he swallows back on it. This boy's already been through so much. The first and most prominent instinct in him, knowing Jack is his child, is to protect, from all things. Including himself.

He failed Claire so profoundly, and now with his own son... He has to do this right, he must.

"No, Jack, you're not a bother at all. I was just, um, surprised." Cas inhales deeply, grounds and focuses himself, and brings his attention solely to the young man before him. Beyond the shock and confusion is a deep, personal joy blooming in his chest Cas can't quite find the words for, but the sentiment of family has never felt more real and true to him. He reaches out for Jack's hand and beams at him, each parts proud and awed. "Jack, it's incredible, it's miraculous to be meeting you here, I don't— It's nothing I ever expected, but I am beyond grateful for it."

The information about Kelly Kline is a new level of baffling, but he's not about to pick his son's brain to resurface all the trauma of losing a mother just for the sake of satisfying questions that have no real impact on the present moment.

"Please know you will be safe here. This new world can be frightening and confusing, but you'll always have your home with us." Cas glances back to Sam, hoping he gets the whole 'let's not overload this four-year-old super being with an interrogation right now' approach. "Arrival is a stressful process. Let's leave the questions for now and find you a room. Alright?"