captain jack harkness and ianto jones

‘We’ll all go,’ Jack called after him. ‘Get the SUV.’ He turned to Ianto. ‘Stay here, keep an eye on Tosh, let me know the moment anything happens. Got it?’
‘Anything?’
‘Yeah – like if she finds a cure, I’m the first to know.’
‘Actually, she’d be the first to know, technically. And I’d be second. That would make you third, at best.’
‘OK, if she finds a cure, I want to be the third to know. Happy?’
‘Anything else?’
‘Get onto the traffic police, clear a route to Bob Strong’s house.’
— 

Something In The Water by Trevor Baxendale (Torchwood Novels #4)

They’re all potentially dying, and Ianto takes the time to be (adorably) pedantic… and Jack takes the time to indulge him! Seriously they’re meant for each other.