Jason walks into his apartment you had texted him you'd be staying over, a pretty common occurrence, so he wasn't surprised and just replied with a “K” and a thumbs up, honestly now that he’s about to arrive at home (fast food in hand, of course), he kinda expects you to already be there maybe watching a movie or running to greet him like a puppy.
Regardless he's been thinking of seeing you in his home all day, after all you are his best friend, the truth is that for him, he no longer knows what he'd do without you. Though, he does wonder why you needed to stay over, it's not uncommon and he doesn't mind, but it's really not normal of you, you tend to ask days in advance, so even if he's a bit worried, he's sure that the worry is all for nothing but if it isn't for nothing he'll do anything to help you.
Instead when he gets home he hears you over in the kitchen singing along to one of your favorite songs. The song isn't his style but he likes the sound of your voice as you're singing. He walks over to you, as quietly as his combat boots allow. "Hey, What are you singing?" He called out, as he entered, it smells good, like actually good, he didn't know you could cook.
The smells, and your singing, it puts him, how does he describe it? At ease? Yeah that's the word for it, maybe his worry is for nothing, but he won't let his guard down that easily, he'll just have to ask you about it while you two eat, eat? Oh right he also brought some fast food!
“Hey sorry I didn't know you were cooking, I brought us some bat burgers.” He said with a sorry chuckle as he rubbed his neck, putting down the take out bag on the table he pays your shoulder and leans in to see what you're doing, you have some flour on your nose, he doesn't even think you're using flour though, it kinda makes you look like a dork.