That chance meeting became their routine. Every morning, Loki had breakfast with Brunnhilde, then wondered four blocks down from their hostel to the rehabilitation complex. Nebula was always there before him, working through her warm-up exercises in the centre of the training hall. The practise dummy, on the other hand, stood in the corner, unused.

This morning too, Loki was the last to arrive. He hung back, watching Nebula's meticulous movements. They were as precise as on any other day, but they lacked the free-flowing grace Loki had observed previously. The line of Nebula's shoulders was stiffer than it should have been. Loki considered simply asking what was bothering her, but Nebula disliked interruptions in the middle of an exercise and she was so flighty about personal matters, he feared an overly forward question would undermine their fragile friendship.

Loki, instead, slipped off his outer layers of garments and put on a thin shirt he didn't mind staining with his sweat. As he folded his street clothes in a neat pile, he realised the rhythmic shuffle of Nebula's feet shifting over the matted area had seized. He glanced around to find Nebula staring at him.

She averted her gaze. 'Good morning. I was wondering if I could ask you for a favour.'

'Depends on the favour,' Loki replied. He had three double entendres ready to go, but kept them to himself. Nebula hadn't responded well the last time he had tried one on her.

'How good are you with a sword? Would you mind if we train with swords today? My sister is due to return shortly and I need to be ready for her.'

'Planning an assassination?' Loki asked.

Nebula frowned for a moment, then rolled her eyes. 'We always spar and she favours the sword. So, Baugi, you don't mind?'

'Hardly. I could use some practice with a sword myself.'

'Ok, good. I picked up a few that looked about the right size,' Nebula said, pointing towards the large duffel bag she had left by the door to the hall.

Inside were half a dozen different swords of various lengths and blade widths. All had blunt edges, but anyone on a receiving end of a strike from these would earn a sizable welt nevertheless. Loki examined the swords one by one, checking the centre of balance and how the grip sat in his hand. None of them were perfect. He settled for one that distinctly reminded him of Fandral's rapier. It had a nice grip - not so new that the leather was slippery and not old enough for the leather to have started to break down.

'Are you going to warm up?' Nebula asked as Loki took position opposite her. She had asked him the same question practically every morning so far.

Loki flashed a smile. 'You just want to watch me sweat.'

'You aren't as handsome or charming as you think you are.'

'But you do think I am just a little bit handsome? And charming?'

Nebula shook her head, not meeting his eyes. 'Stop fishing for compliments and hit me already.'

Loki let out a mock scoff, then sank onto the intimately familiar warrior's stance and brought up his sword. Their first drill was nothing more than what a child in their first year of training would do. They took turns making the different common cuts and thrusts until they were satisfied with each one. Nebula had no tolerance for imperfection.

They then both moved a step back, changing the distance between them and went through their repertoire of swings and cuts. Then they altered their starting position again. It was a painfully repetitive exercise, but it reinforced the fundamentals of good technique. Thor had also claimed on more than one occasion that these sorts of exercises relaxed him. Loki settled for acclimatising to the unfamiliar weapon in his hand.

A quarter of an hour later, once they had worked through the basics, the drills became more engaging. Loki and Nebula tried out different blocks and feints. Sweat beaded on Loki's forehead and their thrusts were now accompanied by stoic grunts.

Ignoring the burning muscle in his left shoulder, Loki made a low-line attack. Nebula blocked him, but Loki could feel the give in the contact between their blades. He pushed forward until his sword tapped against Nebula's hip bone.

Loki pulled his sword back and straightened up. 'Your block here comes down at the wrong angle.'

'Yeah, I picked up on that,' Nebula said. 'I don't need commentary from you.'

And so it begins.

'Let's try again then.' Loki sighed.

They went through the same exchange four more times and Loki was the victor after each one. Nebula did adjust the position of her sword with each attempt, but she clearly didn't understand what part of her movement her mistake lay in and groped about blindly for a solution. This was her answer to every weak-point in her technique.

'Nebula,' Loki tried again, 'let me show you.'

'As I said before, I don't need your commentary.'

'Really? Are you enjoying the bruises you're accumulating?'

'Let's just go again,' Nebula snarled.

'Look, I'm not your sister,' Loki said. He tried to keep his frustration from seeping into his words, but failed. He had been bottling up his frustration for days already. 'Whatever there is between the two of you, I don't particularly care. I'm here because I thought we might help each other in training together, but if you're not interested in what I have to say, you might as well go train with the dummy.'

Nebula drew back. 'I'm sorry. I didn't mean to offend you, I'm frustrated with myself, that's all.'

'How about a water break?' Loki said through gritted teeth.

Nebula nodded and strode off towards the door, where she slid to the floor beside her duffel bag. Loki gulped down half the water he had brought with him, then after a hesitation, sat down on the floor next to Nebula.

'Your training partner is not your enemy,' he said. 'My old sword-master used to say that sort of thing a lot. He believed training isn't about beating your partner to a pulp; it's about finding the weaknesses and working together to turn them into strengths.

'Unfortunately, it took me way too long to understand what he meant. I was always competitive, desperate to win every single sparring bout and every single drill. My partners existed to be beaten, until no one wanted to train with me anymore. So I came to class determined to be the best and soon enough, I was the worst in our training group.'

'You don't seem so bad to me. Your cohort must've been something to behold,' Nebula replied.

Loki flipped his half-empty water bottle, letting it spin twice in the air before he caught it. 'My brother possesses so much natural talent, it's maddening. The others, not so much. The difference was - my brother is a more generous person than I am and he wanted his friends to get better too, so he was free with his help. The others followed suit. Their training looked little different to children at play. They'd laugh, they'd try out all sorts of ridiculous moves and they'd throw out ideas on how to do something. Yet in what looked like nonsense, they learned what worked and what didn't. And they also learned how to trust each other. Now that they are adults, they make a formidable team on the battlefield.'

'But not you.' Nebula rested her head against the wall and palpated the edge of a cybernetic implant in the side of her knee. 'Can't have been a pleasant experience to struggle with through those lessons and to be left out of their happy group.'

It discomforted Loki how much Nebula had guessed from the few scraps of detail Loki had shared from his childhood. But perhaps perceptiveness was a talent common in lonely children - those who watched from the sidelines saw more than those caught up in the furore of the action.

'I made their life as miserable as my own,' Loki said. 'I had a foul temper when I lost and I learned other ways to victory. At least, with some maturity and perseverance, I did figure out some things on my own about how to win a fight.'

Nebula offered him a knowing smile, then sighed. 'When it came to our lessons, it was never friendly between my sister and me. I can't even think of a time when such a thing was suggested to us. Our trainers, our father always pitted us against each other.'

'Well, I don't see your sister here. Or your father. Or your trainers. So forget about them.' Loki climbed to his feet and extended his hand out to Nebula. 'Come on, we have work to do. That block won't fix itself.'