Where you are sent to apparently depends on your character race, got sent to Silvermoon on my BE mage, and to TB on my Tauren druid.
The brain whispers to you while you carry it, for example:
Dual-plagued Brain whispers: Please! <Name>! Destroy me!
Dual-plagued Brain whispers: I have done such vile things...
Dual-plagued Brain whispers: ...killed loved ones... eaten them...
Dual-plagued Brain whispers: Give me your brain!
Dual-plagued Brain whispers: I must feed...
Dual-plagued Brain whispers: Please! <Name>! Destroy me!
Dual-plagued Brain whispers: Let the torture end!
Dual-plagued Brain whispers: Show mercy, <Name>! Give me peace!
Dual-plagued Brain whispers: [Zombie] .. .... . brains .... .... ..... .. ... ..... ..
Dual-plagued Brain whispers: My King knows of you. He wants to see you...
Couldn't get it to whisper to me while I was a Zombie, so I can't tell whether the [Zombie] part actually has meaning.
PS: Lore hint: In e.g. Silvermoon and Orgrimmar the turnin NPCs are near the Boss leaders, but in Thunder Bluff, it is in Magatha's tent... WTB more Grimtotem lore, though I despise them, they offer a really nice insight to the "dark side" of the Tauren. A dark-skinned Tauren will also be my choice for a DK.