I would beg to differ. I imagine a backstory of TK-421 as the Imperial Army's version of Gomer Pyle, USMC. He is a good soldier but not the most accurate blaster in the armory. He is probably always getting into innocent mischief, like that time he got his armor mixed in with the Imperial Guard's laundry and he he had to wear Pink Armor for a month. You could even hear it in that Lt's voice when he radioed down to him. "TK-421, why aren't you at your post?" You could almost here the implied "again!" at the end of his sentence.