Love-at-Arms by Rafael Sabatini

Well indeed had it been for Ser Peppe had he restrained his malicious mood and curbed the mocking speech that had been as vinegar to Gian Maria's wounds. For when Gian Maria was sore he was wont to be vindictive, and on the present occasion he was something even more.

There abode with him the memory of the fool's words, and the suggestion that in the heart of Valentina was framed the image of some other man. Now, loving her, in his own coarse way, and as he understood love, the rejected Duke waxed furiously jealous of this other at whose existence Peppe had hinted. This unknown stood in his path to Valentina, and to clear that path it suggested itself to Gian Maria that the simplest method was to remove the obstacle. But first he must discover it, and to this he thought, with a grim smile, the fool might--willy-nilly--help him.