J is for Join
Often, if a task is important, Starscream would prefer to do it himself. Carrion knows that his Commander sees everyone else as, on some level, incompetent. He's a surprisingly arrogant mech, for one who has never fully realized his ambitions.
And that wasn't fair, or necessary, he chided himself as he went about the dull task of updating the system specs of some bridge-dwelling drone. Starscream's goals were lofty, indeed, and every motion he made brought him closer to their full completion. The young jet has personally witnessed him talk even Lord Megatron in a circle. He was always in full command of almost every situation he enters in.
That is why he leaves Carrion on the Nemesis when he has something dangerous or delicate to do. Because he must be in control and he can't have there being any chance of things going awry. His place as the Commander's bonded was to do as he was told, to stay where he had decided he was needed, and be here when he came back.
Carrion understood it and did his best to play the good little bond-mate. And yet, it still stung every time he was not invited to join his Commander's task force.