A puzzling aspect of TSS brought up in discussions on the Quiller Mailing List concerns whether or not the espionage professional is entitled to hold a grudge against those s/he counts as opposition in the field.  Although Q eventually comes to the conclusion that, at least in the case of Schrenk, espionage dirty tactics do, finally, become personal, during the interview with Steinberg, he thinks it is inconsistent for Schrenk to have held a grudge or to have been bitter ("we don't harbor grudges against the opposition" [3:30]).

If we take the dictionary definition of "grudge" ("a feeling of deep-seated resentment or ill will"), we find that, apparently, Quiller is not only adept at deceiving others, but himself as well.  Below I have listed three famous grudges Q's held against the opposition in this and earlier QBsOTM:

1.  Heinrich Zossen.  Speaking to Pol in TB/QM, Q complains that they no longer hang war criminals.  Then he says:  "Give me a rope, though, give me a rope and ask no questions."  Even Q realizes how extravagant that degree of resentment is, so he immediately mumbles an apology about being tired.

2.  Kuo.  In a similar situation in T9D, Loman has to come upside Q's head when he goes on an emotional binge after Kuo shoots the Person's driver, causing the limo to plow into a crowd of people, killing several.  '"No, but the rest was enough.' I twisted the telephone cord, garroting my wrist. 'We don't know how many dead do we? I think he's a bit of a shit and I'm keeping my gun, the Husqvarna, never know your luck.'"  Loman is obliged to reprimand Q for this indulgent lapse in professionality, telling him to make his report "a little more precisely."

3.  Satynovich Zade.  In TKM, Q vents his deep-seated anger against Zade's abduction of Pat Burdick:  "In my trade we don't take things personally or if you want to put it another way we take things about as personally as a pilot does when he drops his bombs. But when I killed Zade it would be with a sense of satisfaction."  This is an extraordinary degree of resentment, because it not only posits being emotionally satisfied by murder, but is unprofessional in allowing a specified outcome to the mission (Zade's death) to dominate the end phases of the mission (thereby negating other potential solutions, such as negotiation, exchange, barter, blackmail, and so on).

Of course, the most famous example of a Quiller grudge occurs in this month's QBOTM, "The Scorpion Signal," where Q takes an insult about personal hygiene as an excuse to kill four men.  I think Hall was pursuing a theme here, allowing us to see the evolution of Quiller's worldview, as he moves from impatience with Steinberg over why Schrenk should have had a grudge, to his own humiliation at the hands of Vader, and finally to the realization that anyone who's gone through as much as Schrenk has every right to hold a grudge.  Thus, not only does Q hold grudges, they're one of his most effective tools for self-motivation.