Tony stared at his hands, not quite able to form any coherent sound.

Moments ago he had held Peter; now there was nothing. He had seen many dead people in his life — the pale, the discoloured, the swollen, the mangled. As degraded and distasteful as death often was, there had always been some remnant of the person left behind. Now there was nothing. No even ash floating through the air or dust clinging to Tony's fingers. Peter was obliterated from existence, only the echoes of Peter's last, panicked cries remained to roar through Tony's mind again and again and again.

'Come on, get up,' Nebula said as he slipped her hand under Tony's armpit.

Tony shrugged her off. 'What's the point? Thanos did what he wanted to, didn't he? It's too late.'

Nebula grabbed him by the collar of his shirt and pulled him up until they were looking eye to eye. Her face, humanoid yet undoubtedly alien, was twisted into an ugly expression.

'He killed my sister; he will pay for that,' she said. 'He killed your friends too. Knowing this, will you do nothing?'

My friends. Tony's ever-unhelpful mind summoned the familiar visions of Earth's desolation and the cold remnants of everyone he cared about. Was it better to have died in battle as he had imagined it? Or was it better to have simply crumbled into nothing, not even understanding what was happening? Tony ran his hand through his dust-coated hair. No, Peter had understood what was happening to him perfectly well.

'It's too late.' He shrugged. 'We had our one chance, one out of however many million and we failed.'

'Your friend gave up his infinity stone for you.'

Tony scoffed. 'Friend? I barely knew Strange. The jury was still out on whether I even liked him.'

'Then the point stands even firmer,' Nebula replied, cocking her head. 'Why would he give up an infinity stone for a stranger? He said —'

'Oh. I see,' Tony muttered under his breath, then continued more loudly. 'You think the fuck-up here is a step on the path to defeating Thanos.'

'Strange knew more than he told us.'

'Well, if that's true, it would have been fucking helpful if he'd shared his knowledge with the class instead of sitting about, making snarky remarks about everything and everyone.'

Clenching his fists, Tony turned away from Nebula and kicked a coiled piece of what might have once been the wing of a ship. It rolled a dozen feet before it slammed with a loud clang into the remnant of a wall. He stared at the cracked bricks. Tony was in the mood to break something, but everything around him was already shuttered and crumbling.

'Strange saved you,' Nebula pressed. Her eyes focused on something a quarter mile past Tony as she frowned. 'Your life is crucial to the outcome. Somehow.'

Tony bit back the uncouth retort on the tip of his tongue, then threw up his hands. 'Do you even know where Thanos is?'

'There is no place in the universe where I won't find him,' Nebula replied. 'Come on, let's return to the ship.'

She strode off without waiting for Tony's response. For a long moment, he stood there, watching her climb through Titan's wrecked landscape. Then he sighed and scrambled after her. No matter how events played out from here, there was no point staying amid this desolation millions of miles from home.

'Where do you plan to go?' he asked once he caught up to Nebula.

'I'm not certain yet,' she answered. 'Perhaps I'll try to get information from the Chitauri. No, it'd be more useful to track down the Black Order and get them to talk.'

'Could you take me back to Earth first? I-I left my fiancée behind.'

The thought of Pepper hitched Tony's breath. Was she still alive? She had to be. She absolutely had to be. He didn't know what he would do with himself otherwise.

And he would have to go to Peter's aunt and explain why Peter had never come home from his school excursion. And what was the name of the guy with Strange back in New York? Wong? Tony would need to find him and let him know about Strange. It was the least Tony could do to repay the sacrifice Strange had made in exchange for Tony's life.

But what if there was no one to tell about Peter and Strange? What if —

'Hey!' Nebula said sharply. 'You need to breathe.'

Tony gulped down the breath he hadn't released he'd been holding, but it didn't make him feel better. His hands trembled and his knees threatened to collapse under him. He sank down to the ground before his own body betrayed him.

'Pepper and I were supposed to get married next month,' he muttered. 'A smallish wedding, Pepper didn't want it big, just the people we really cared about on the invitation list. But, but what if there is no one left from that list? Just… empty space. I can't get married like that. I can't live like that, knowing that I didn't… didn't stop him when I should've. As if Pepper would want anything to do with me after this. Not like that matters of course, I just hope she is ok. She…'

Nebula crouched down beside him. 'We will find out soon. I'll take you home.'

'Thanks,' he said. Nebula shifted away from him and something within Tony snapped. 'How are fuck are you so calm about this? Half the universe is dead.'

'But I'm alive,' Nebula replied.

'So am I and I don't feel calm in the slightest.'

Nebula chuckled. 'I'm not calm, I'm furious. But I am also focused. Even if I have to tear apart the universe twice over, I'll find Thanos and make him pay for what he did.'

Tony slid his thumb over his arc reactor, then sighed. 'Take me back to Earth. Whoever there is left, we'll help you hunt down Thanos. I suppose it's fitting – we came together to avenge Earth, now we'll get to avenge the universe.'