“I'll make a bargain with you.'
...
Cassian maintained a casual stance. 'If you do an hour of exercises right now, I'll owe you a favour.'

'I don't need any favours from you.'

'Then name your price.' He struggled to calm his racing heart. 'An hour of training for whatever you want.'

'That's a fool's bargain for you.' Her eyes narrowed. 'I thought you were a general. Aren't you supposed to be good at negotiating?'

His mouth quirked upward. She wasn't fighting him. 'For you, I have no strategies.'

She studied him with unflinching focus. 'Anything I want?'

'Anything.' He added wryly, 'Anything short of you ordering me to fall out of the sky and smash my head on the earth.'

She didn't smile the way he'd hoped. Her eyes turned to chips of ice. 'You truly believe me capable of such a thing?'

No,' he said without hesitation.

Her mouth tightened. Like she didn't believe him.
...
She surveyed him again, and Cassian willed himself to stand still, to appear open and nonthreatening and not like his very heart was in his bloody, outstretched hands.

She said at last, 'Fine. Let's just say it will be a favour. Of whatever size I wish.'

It was dangerous to allow this. Deadly. Stupid. But he said. 'Yes.'

He extended his hand. One last time.

Keep reaching out your hand.

'A bargain.' He met her steely expression with his own. 'You train with me for an hour, and I'll owe you one favour of whatever size you wish.'

'Agreed.' She slid her hand into his and shook firmly.”