Tinker and Kazam are two volunteers for the San Pasquale Militia who guard the upper entrance of the village.
The two unnamed militia members at the lower entrance refer to them as the chatterboxes at the upper entrance, and talkative they are. Scarlett can ask them for information about the blocked pass to Venice, get some general tips, and -- of course -- allow them to explain their own duties.
At the very beginning of the game (before Scarlett completed the Proper Clothes quest, Tinker & Kazam will block her exit to the mountains; the militias at the lower entrance will do likewise.