Binding of Isaac Afterbirth Character Starting Item Unlocks

Isaac	- The D6		- Beat Isaac with Blue Baby
Maggy	- Speed Up pill		- April Fools challenge
Cain	- Paper Clip		- Donate 68 coins to the Greed Machine
Eve 	- Razor Blade		- Donate 439 coins to the Greed Machine (beat Satan with Eve first)
Samson	- Child's Heart		- Ultra Hard challenge
Lazarus	- Anemic		- Backasswards challenge
The Lost- D4			- Destroy 30 slot machines
The Lost- Holy Mantle		- Donate 879 coins to the Greed Machine
Lilith	- Cambion Conception	- Beat Blue Baby with Lilith
Keeper	- Wooden Nickel		- Beat Isaac with Keeper
Keeper	- Store Key		- Beat Satan with Keeper
Keeper	- a penny		- Beat Hush with Keeper