This is turning out to be a bit more like cuddling than huddling, but Steve doesn't mind. It's strange sure, but he lets them both press as close as they need. He's their space heater right now, so long as he keeps Natasha warm, he doesn't care much how it happens.

Once Natasha is more settled, he rests his arm across her, placing his hand against Bucky's side. It's a light weight to offer warmth, but also there to remind the two of them of his presence when they wake up later. He rather they didn't forget about him and punch him in his sleep. Not that he thinks they will forget, but he rather not chance it in such a high stress environment and with Natasha being so out of it. Better to play it safe.

He knows it'll be a while before he relaxes into sleep, wanting to stay up and keep watch as he lets them sleep safely.