Sometimes, it sucked to know two people you're travelling with as well as Sam knew Dean and Gabriel.
Gabriel had joined them some time after the whole thing with Castiel and the Leviathans went down, after Bobby's death. That is, he'd appeared on the floor, panting heavily, looking small and weak. Dean had lifted him onto his bed where he lay without waking up for two days. He recovered from that after pizza and Pepsi, and explained that yeah, he had been dead, but now he was back and regaining his powers.
It was a very slow process, but he could poof around and wield a knife, and Dean taught him how to handle a gun. And they were much better off for the back-up and angelic knowledge.
The day Gabriel first recovered and realised he needed food, he began carefully counting calories and came up with a meal plan for himself so he wouldn't get sick from over- or undereating. Dean laughed himself silly over it. He was not, however, laughing when he opened the bathroom door and a bucket of mud inverted itself over him. Gabriel then explained to Sam that he knew that human bodies needed taking care of and he couldn't just gorge himself with candy anymore and he meant to be of use to them.
Otherwise, he was still very much Gabriel. It was funny, because apparently he had worked as a stagehand for Led Zeppelin and AC/DC concerts for a while, and Dean nearly wet himself when he found out. Sam had then been wrestled into the backseat and the two gushed about them the entire trip to a hunt. It was really cute.
Sam noticed when Dean first came back from the gas station with a bar of Cadbury along with the snacks they usually had when they spent a night driving. Gabriel hadn't noticed - at least, he looked surprised when he tried to snatch the Kit-Kat Dean was eating and Dean brandished the chocolate at him instead. Later, Dean learned to use candy as bait to make Gabriel do something for him (sadly, Sam was usually not involved in the benefits) because Gabriel could no longer simply will food into existence anymore. He'd go so far as to dangle it a foot away from the angel's face and taunt him into getting away from the television or shower or whatever it was Dean wanted from him. The pathetic part was that it worked every time. Even when he started earning his own money (hustling pool; he was really good at it).
And Gabriel had these really nice eyes. Sam wasn't saying it because he noticed or anything; it was just that Dean was apparently as weak to those eyes as he was to Sam's own puppy face. It was kind of sad sometimes to see him try to decide between the two when the choice should obviously be Sam because he was Dean's brother, for God's sake!
As if that weren't enough, there was that one time -
'I don't want to sleep on the floor tonight!' were Gabriel's first words when they stepped into the motel room.
'Duke it out with Dean, I've already spent two nights in a row on the carpet,' Sam said, dropping his things on one of the beds.
'Fair's fair, Gabe!' Dean barked.
'But Dean!' Gabriel whined, dragging out the name. 'It's not comfy! I won't sleep!'
'Well maybe that's your angelic powers returning.'
Gabriel looked alarmed. 'No it isn't! I meant that I wouldn't be able to sleep properly, then next thing you know, I'll fall asleep in the middle of a hunt and -'
'Okay fine, you know what? You can sleep with me.'
'- you guys would blame it all on me and - what?'
'I said you can sleep with me,' Dean snapped. 'In the bed. Now stop complaining, you sound like a girl.'
In the morning, Sam was woken up to Dean muttering 'Gabe, wake up dammit! You're squashing me!'
Sam couldn't see what was going on underneath the covers, but he could see Gabriel nuzzled up to Dean, his face in the hunter's neck.
'I can't breathe!'
'Shut up,' Gabriel mumbled sleepily, burrowing closer to him. Sam noticed that Dean's hands weren't actually anywhere to be seen.
He groaned and turned over. He didn't need to see them in their weird mating dance.
Other than all the lovey-dovey chick-flick moments that Dean had allegedly sworn against early in their career as Apocalypse-busters, they also fought a lot. When candy-baiting and pranking failed, they'd resort to loud words and mean remarks. It almost always ended in a carelessly flung word, a shocked look, and the insulted party storming away. And they never apologised. The next day, or the day after, or whenever they felt they were through hating each other, they'd go back to sleeping in the same bed or whatever and act like it never happened.
But that wasn't the worst thing, oh no. The absolute worst, most embarrassing, hands down awful part was that they tried. Dean would be about to leave the car and Gabriel would reach out, then suddenly drop his hand and Dean would be none the wiser. Or Gabriel would be resolutely watching TV with his mouth in a thin line, and Dean would scratch the back of his head and shuffle his feet then shrug and turn away.
It was so stupid and Sam had had enough.
'I am so sick of you guys!' he yelled, slamming the book he'd been researching shut. Dean and Gabriel whipped around to look at him, Gabriel shutting the mouth he'd opened in another failed attempt to apologise.
'Something wrong, Sammy?' Dean said.
'Do you know what the problem is with you two?!' Sam demanded, ignoring Dean. 'You're both stubborn asses! You both like each other so much that neither of you are willing to admit it so you just sit there and yell at each other then cuddle on the couch and drink each other's beer!' He took a deep breath, briefly cherishing the dumbstruck looks he was receiving. ' That's not even the worst part! The worst part of it all is, you both keep trying, but you're both such cowards, you back down before the other even notices! Well I've had it with you guys!' He picked up the book, his jacket, and the Impala keys. 'I am going to have lunch, and I'm not coming back until you've worked things out between you!'
And then he stormed out, feeling just a little better.
When he came back several hours later after having found out that much more about their case, it was to Gabriel sitting comfortably on Dean's lap, the two sharing a slice of pie which, judging from Gabriel's triumphant expression, the angel had conjured himself.
'You guys are so cute,' Sam said.
Dean threw a pillow at him.
Sam was going to lord that smile over him for the rest of his life.