Intelligence

Intelligence, when referring to a Muttly demon, is a permanent, unchangeable property of a demon. It corresponds to speed of thought and affects the demon's ability to concentrate on more than one thought. (Stability also affects this.)

Demons do not think with physical brains (see below), so that 'intelligence' is innate and does not change if a demon shifts into a shape with a bigger head.

What do they think with, then?

Demons are shapeshifters. This isn't just an ability; it defines them. Their attachment to physical matter is not complete. Most of them have low enough shapeshifting skill that they couldn't survive without a body, but some can for varying amounts of time.

In any case, demons' thoughts and memories are not stored in their heads, but in their non-physical aspect. They 'think' with their intangible side.

Most demons are, by most other sapient species' reckoning, stupid.

Technically...

A demon with high enough shapeshifting skill might actually be able to build a functioning brain and use it to think with. It would need to be a stunningly talented genie for this to work.

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