They can't help but look when the other isn't watching. Remus will glance up from his book as Sirius steps dripping and clothed only in a towel, flicking his too-long hair back in a way that would be feminine if it wasn't him doing it. Remus's eyes are only on him for a second before he quickly refocusses on the page he was previously looking at.
And then it's Sirius's turn. He saunters into the dormitory, all the while sending Remus cursory glances to see if he's watching him, paying him attention, looking at his Quidditch-toned abs.
But he never is, because Remus is too careful. Sometimes their eyes do meet, and they'll smile politely at each other before going back to what they were doing, both pretending it was nothing, thinking that the other thinks it's nothing.
And then James and Pete will exchange glances; James in exasperation, Peter rolling his eyes with the faintest hint of amusement. And they both know James wants to stand up, bang their heads together and yell "We know, morons! We all know, except you two." But he doesn't, and James and Pete look away from each other before the other two Marauders can see the look passing between them and guess its meaning.
And then they'll go down to breakfast, where they can look at each other in turns over bowls of cereal and porridge. That's when Lily and James take their turn. Lily looks over to the Slytherin table, pretending that she doesn't care that her best friend is dining with Death Eaters. Sometimes Severus will meet her eyes defiantly and she has to look away, the flush of shame tinging her cheeks. But otherwise she just watches, and completely misses the doe-eyed looks she's getting from James.
In turn, James doesn't notice that he's on the receiving end of one of these looks from a Ravenclaw girl sitting a few places away. Peter knows her; he sometimes works with her in Potions. Her name's Melody, and she's really nice and super intelligent. But he's willing to bet that James wouldn't even recognise her if they met out of school.
So he just watches the drama unfold as everyone looks and doesn't look and looks away. And he wonders how much easier life would be if they'd all just open their eyes and realise exactly who's looking at who. If they paid attention to what mattered and saw rather than just looking all the time.
But then again, he thinks, maybe things wouldn't change at all.
It's all in the glances. Those small glimpses that they take of each other as they peek through their fringes or over the tops of books. Those odd looks that no one ever notices except for him.