Loto saw someone who he thought was his father, and they spoke right too and knew his name. Thunk did not trust them and imposed himself between them and Loto. Loto went and approached them, despite Thunk's warnings.
Also this is the first time seeing thunk in one of his 'aspects' This one is the aspect of Telto the Murkrow. It darkens his feathers and makes him invisible against the skyline at night time.