Agatha meets Hezekiah Donowitz on his way to Theo's room, where Gil is holding forth about his time at university in Paris, now that he has been reunited with his friends and some misunderstandings clarified. Hezekiah had likely been friends with Gil before he left, when nobody knew who he was in the larger sense of things.
Hezekiah apparently had been put in charge of refreshments, as he is seen carrying several bottles with interesting labels: Dynamo Wine, Whale Ale, One Mean Mead, Cyclops [obscured], Old Upside Down Ale, Aqua Regia, Formula 73A, Spark Gap, Oktober Frenzy, Blue Lightning, Potato Surprise, Drink Me, and a few others harder to read.
He wears the Wulfenbach badge on his right vest lapel, and a badge on his left lapel that is not yet identified, but is comprised of vertical and horizontal crossed lines, with a diagonal connecting the ends on the lower left quadrant and upper right quadrants, looking much like a plotted equation.
Given the yarmulke and his general appearance, Hezekiah is presumably Jewish. Since few other characters have any overt signs of religious affiliation, one may wonder if he is only culturally Jewish or if most characters simply do not practice any religion in particular.