This wasn't anything new.

It's not like he never had problems sleeping, it's just, the images, of crashing into the ice, of Bucky, the last words Peggy ever spoke to him... Tony. Tony free-falling from the portal, Tony laying there, helpless on the ground the arc reactor blank, omitting no light.

He'd wake up, breathless, cold. Panicked. It would take him a few long, deep breathes of reassurance that he was, indeed, in a bed, next to a human form tangled in the blankets next to him. That he was next to a one, Tony Stark. Tony would, of course, be awake by the abrupt movement next to him and card his hands through Steve's hair slowly calming him until the Captain fell back to sleep, wordlessly.

It was on those occasional nights when Steve would be so frightened and anxious, where Tony took almost desperate measures and started humming forgotten lyrics to songs. They would be soft and gentle, a side of himself that Tony reserves only for moments like this. He would hum the lyrics, slowly allowing the super soldier to relax into the sound, the vibration in Tony's chest. Steve felt grounded. He didn't feel like he was about to crash the plan into the water, or seeing a hand stretched out towards him that he was never going to reach.

Sometimes, if Steve was lucky enough that humming would turn into words.
Tony's voice never ceased to lull Steve back to sleep. The contempt feeling of having his lover flush against his chest, breaths slowly cascading over his skin as Tony sang to him, and his eyes fighting to stay open. It was just enough to keep away the nightmares.
It even worked when Tony was halfway across the world.

Tony had to take a business trip to Japan for a merger meeting and to talk about stocks... or something along those lines. So, Tony wasn't next to him the night when Steve woke up screaming almost bloody murder.

"JARVIS..."

"I've already got Sir on the line, Captain."

Steve took a shaky breath, tears threatening to escape as he did.

"...Tony?" His voice was soft though drenched in terror, coming out more cracked then he hoped.

There was a faint click, as if a door were being locked followed by Tony's voice.

"Shh, hey, I'm here, what's wrong?"

Before Steve could even answer, Tony, being the genius he is and claims to be, talked over the silence.

"Nightmares... right. Uh, are you okay? Wait, no of course you're not okay you had a nightmare and you're calling me at what, what time is it there, it's 3:00 pm here so... 2 in the morning or something? Steve-" Tony was cut of by a sniff at the other end, followed by a heavy, shaky sigh as Steve slowly let himself sink back into the bed, listening to the sound of his boyfriend's voice.

"Steve?" Tony said in a softer voice that Steve would like to think was only for him.

"Sing to me? Please...?" Another small sniff escaped him and he winced a little at how desperate he sounded.

"You want me to... right now?" Steve nodded, even though the other couldn't see him.

"It's... It's the only thing that helps when, it's this bad Tony please..." Steve let out a chocked voice as tears fell from his eyes, staining the pillowcase underneath his head.

There was a couple moments of silence and just as Steve was about to apologize for asking, a slow, slightly muffled and off tone voice swept over him.

"I don't wanna live in yesterday
Cross my heart until I die
Don't wanna know just what tomorrow may bring
Because today has just begun
No matter whatever else I've done
I'm here for you
I'm here for you"

He closed his eyes at the sound, already feeling some tension leaving his heavy shoulders as Tony continued in the same hushed voice that Steve loves and craves on nights like this;

"So now I sit here and I wonder
What ever happened to my friends?
Too many bought a one way ticket
But I'll be with you 'til the end"

Slowly but surely, Steve melted into the words that were surrounding him like a blanket, all the tension seeping out of his body as he let the sound of Tony's voice bring sleep to him. Tears still stained his face as his breaths got softer and less frequent, slowly, sleep overcame him once again.

"Steve?" Tony muttered a few moments after he finished singing. When he didn't get a response back he smiled lightly to himself.

"Sweet, dreams, Capsicle."

Needless to say, Steve slept through the rest of the night without another nightmare, and Tony still halfway around the world.