In "Small favor", Harry has to fulfil the task for Winter Queen Mab and save Marcone and Archive/Ivy. At the same time the Summer Queen Titania sends her
assassins champions to kill him as a payback for the death of Summer Lady Aurora. When confronted by the Eldest Gruff (that seconds before swatted Fallen Angel's host like a fly), Harry plays the gambit, asking for repayment for the boon, promised once by Titania:
I tilted my head and stared hard at him. “You say that you serve Summer and the Queen. In that order? [...]” Indeed,” he said. “You were made an Esquire of Summer, and granted a boon, but…” He shook his head. “A boon can be a matter of importance, but not one this grave. Thou canst not ask me to yield to thee in a matter of conflict between the Courts themselves.” “I won’t,” I said. “But just so we’re clear. Once both of us have left this island, the matter is closed?” “Once thou art safe again in Chicago, aye, it would be. ” “Then I ask for Summer to honor its pledge to me, and the debt it incurred to me when I struck at Winter’s heart on its behalf.” The gruff ’s ears stood up, facing me. “Aye?” “I want you,” I said, “to get me a doughnut. A real, genuine, Chicago doughnut. Not some glamoured doughnut. An actual one. Freshly made.”
Why is he supposed to be safe again in Chicago? What stops Summer Queen from sending her goons again after him later on?