In Fable 3 for the Xbox 360, there are six demon doors scattered around Albion that you can open for hidden treasures. To open each demon door, you’ll have to perform a specific task to please the door enough to open it.
Aurora Demon Door
This demon door simply wants you to be 100% good or evil. Once you are 100% in either of these, the door will open for you and you’ll find a legendary weapon inside.
Brightwall Demon Door
This demon door wants you to bring a child to it. It will need to be your child though, since the only children you can hold hands with in the game are your own.
You can either have your own child through the normal means, which would require the Family and Lover Expression Packs, buying a house, marrying someone and having a child that way.
Alternatively you can adopt a child from the Bowerstone Orphanage after you complete the Bowerstone Resistance quest and become the ruler of Albion, and choose to create the Orphanage instead of the Brothel.
Whichever method you choose, simply lead your child to the door to open it. Inside you’ll find three Summon Creature Potions, and 25 Guild Seals.
Millfields Demon Door
To open this demon door you’ll need to be extremly unattractive.
To pull this off, you’ll need to be fat and dress awful as well. To check your weight, look at your Hero Status in the Sanctuary. You’ll want this meter to go all the way to the right. Do this by eating lots and lots of food and booze until the meter is maxed out.
In order to be awfully dressed, the easiest method is to wear your pajamas and color them mismatching colors in the Sanctuary. Try to wear ugly facial hair, and tattoos as well.
Once you’re fat and ugly, the door will let you in where you’ll find 40 guild seals.
If you’re having troubles getting it to open, try sleeping in a house nearby after you’ve made your changes. Some people have reported that this may help the door recognize all of the changes you’ve made.
Mistpeak Valley Demon Door
To open this demon door you’ll have to perform acts of love and kindness in front of it. One way to do this is to either bring a coop partner, or use a second controller profile, and propose and marry the person in front of the demon door. You’ll need the Family and Lover expression packs from the Road to Rule to do that though.
Alternatively, you can go through all of the positive expressions in the game to your partner in front of the door to make it open. Obviously this method is the much easier option.
Inside you will find a legendary weapon.
Mourningwood Demon Door
To open this demon door, you’ll need to have maxed out either your ranged or melee skill to level five. Also, you need to have upgraded all three abilities on any legendary weapon.
Once you have both of these done, bring out your fully upgraded legendary weapon in front of the door to open it. Inside you’ll find a Military Costume and a Summon Creatures Potion.
Sunset House Demon Door
All that needs to be done for this demon door to open is for you to be the ruler of Albion.
Inside you’ll find 1,000,000 coins for your character.