The dead are singing. Barlowe just hums.
They don’t seem to want to include him in their interlocking hexagons, but they don’t mind his tagging along. They’ll form up and shuffle after some whiff of blood (as strong to him, now, as the taste of blue cheese); if the source is behind any particular obstruction, they’ll complain and bump into each other for a while. On scavenging missions (never on hunts) Barlowe smashes the wall open and lets them feast.
They’re not really digesting when they eat–he’s figured out that much. They’re liquefying it, preparing it, like ants or pigeons.