Artificial intelligent assistant

A mythical/legendary/demonic creature that steals talents or abilities I swear I heard about this a long time ago but I can't remember it for the life of me (to the point that I am beginning to doubt if it exists). I faintly remember some type of monster that was able to mimic or outright steal the abilities of other people... Can anyone help me out here?

* The Mead of Poetry is a prime example. The power is transferred not once, but twice:



Kvasir was a man considered most wise, who is murdered by a pair of dwarves. The motivation of the dwarves is to create a magic potion that would confer this wisdom to any who drank it.

Odin, likely not content to allow such a power to be freely accessed, uses trickery to steal the mead, and is mostly successful. (The part that spilled confered a lower form of capability in simple rhyming, while Odin himself keeps the greatest form of the gift to bestow at his discretion.)

* Mimir is another such example:



When Mimir's severed head is sent to Asgard, Odin uses magic to re-animate it, and afterwards benefits from Mimir's knowledge and secrets.

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