Is there anyway to change JerJerrod's character in ROTJ so that he's not so cowardly around Vader?

In ANH, Moff Tarkin and the others are almost totally dismissive of Vader. They outrank him and he's only hangin' around to impose fear on behalf of the Emperor.
Then Vader was suddenly the Big Boss in ESB, but I always thought that was becasue he's on his own ship, around his own crew and on his own secret mission.
Then in ROTJ, he's outranked and back to his old job of "motivating" the crew. Yet JerJerrod treats him as if he's the Emperor himself.
That doesn't add up to me.
JerJerrod is supposed to be a "Moff" like Tarkin was in ANH, so shouldn't he command the same power as Tarkin and not be so sniveling towards Vader?

This is one reason I wish Tarkin had survived the first Death Star. Having him show back up on the new DS greeting Vader at the beginning of ROTJ would have been perfect.