Finally he says, "Those men deserved it," and left it at that. It's too dangerous to get attached, and Serig already knows that at least Dree has experienced killing before. He wanted to leave it at that, and wait for Alben to go on his rambles yet again—Serig is getting used to it at this point—but one thing from Dree's story caught his attention.
"Is your father human?" he asked. Most of his knowledge of elves come from his pack's polite, if distant, elven neighbors in the forests he once lived in, and they, to put it lightly, did not get along with humans. The rest of his knowledge are from the few scattering of elven adventurers he had come across over the years of his wandering, and they were, for the most part, friendlier to humans. Since he's better at distinguishing his fellow beastfolk, it never crossed Serig's mind that those elven adventurers could in fact, have the same mixed heritage as Dree.