Villager Reputation

Trading

Trading	Trading adds 2 reputation with that villager, up to 25. These points drop by 2 every 20 minutes. Trades made in the same instant with shift-click count once.
Curing	Curing a Zombie Villager gives 125 reputation with the cured villager: 100 permanent points and 25 temporary points.
Temporary cure bonus	The 25 temporary points drop by 1 every 20 minutes and are gone after 8 hours.
Repeated cures	Curing the same villager again does not go above 100 permanent and 25 temporary points. It only refills the temporary points to 25.
Hitting a villager	Each hit costs 25 reputation with that villager, down to -200. This penalty shrinks by 20 every 20 minutes.
Killing a villager	A kill costs 125 reputation with every villager that saw it, down to -500. This penalty shrinks by 50 every 20 minutes.
Reputation range	From -700 to 150 with a single villager.
Fading	Each villager runs its own 20-minute timer for these drops, so they do not happen at a fixed time of day. A part that falls below 2 points is removed.
Shared reputation	Villagers that meet pass reputation on to each other at a reduced value: 5 lower for the temporary cure bonus, 20 lower for trading and hits, 10 lower for kills. The permanent cure bonus is never passed on.
Price effect	Reputation x the trade's multiplier (0.05 or 0.2), rounded down, comes off the price. At 125 reputation a trade is 6 or 25 cheaper; at 20 reputation it is 1 or 4 cheaper.