Answers are never the same. All answers are completely randomized. The only way to complete the brain tree is to actually do the esparagor quest twice to get both of the answers for the Braintree quest. Go to the brain tree and started a quest, then feed the esophagor, so you'll know the date. Then feed esophagor a second time. Go and tell the brain tree, and will give you either spooky petpets, attack forks, or spooky food.
Here is a list of Brain Tree Answers, you can try them all you want, try different combinations, anything and everything, but you still have to do the complete quest.
Frank Chia when: 25 BN where: Mystery Island
Frank Jetsam when: 39 BN where: Upper Neopia
Frank Von Currywurst when: 39 BN where: The Great Cliffs
Frank Wilberforce when: 45 BN where: Skull Rock
Helen Brooglemeister when: 18 BN where: Maraqua
Helen Chia when: 51 BN where: unknown
Helen Flotsam when: 39 BN where: unknown
Helen Jetsam when: 41 BN where: The Haunted Woods
Helen Kiko when: 39 BN where: unknown
Helen Nimmo when: 39BN where: Maraqua
Helen Skeith when: 35 BN where: Maraqua
Helen Van Tramp when: 39 BN where: Maraqua
Helen Vaughan when: 26 BN where: unknown
Helen Von Borovan when: unknown where: unknown
James Chia when: unknown where: unknown
James von Cybun when: 39BN where: Virtopia
James von Tramp when: 35BN where: unknown
Kevin Browslovak when: 25 BN where: The Haunted Woods
Kevin Sloth when: 34 BN where: unknown
Kevin Techo when: 70 BN where: In the Graveyard
Kevin Wilberforce when: 31 BN where: unknown