Red is the Color of Wanting
Normally they fly when the sun is fully up, the light giving them a better view of the terrain without the extra effort of switching into night vision. But sometimes the Air Commander insists on drilling routines at night, or early enough in the morning that is may as well still be night.
Because, Starscream insists, there may well come a day when they are called into battle under less than favorable circumstances. He brooks no argument and accepts no excuse for Carrion's early ineptitude when it comes to flying in the dark. He simply pushes him to try harder, to go faster; get back in the air and try again, foolish scrapling.
This is all right with Carrion, who expects nothing less from the brilliant mech that has so enamored him. He appreciates the strain, even as he complains; he welcomes these arduous early mornings because it's always just them, and he is learning. He's never had anyone spend enough time with him for his processor to really sync with a lesson that wasn't medical.
But when the sun starts to rise, and the sky bleeds through in shades of red and gold, he's not thinking about the lesson anymore. He's watching his Commander, soaring in alt-mode or standing in his regular form; red light making his sharp features all the sharper, making him look somehow more dangerous and strong as he glares at Carrion.
Keep moving, he'll snarl if he catches the young jet staring, and Carrion will. He'll do anything Starscream asks, despite protesting, because when he sees the older mech awash in the red light of early morning, his spark clenches with something he can't define, and all he wants is for the Air Commander to see him, too.