What is the darkling personality?

Solution 1:

It's just the 2 different darkling outfits you can choose your darkling to wear. Hooligan is the standard one and Abdul is the 'Crazy Abdul' outfit that you get with the limited edition version of the game. As far as I'm aware, it does not affect the game in any other way apart from the appearance of the darkling.

Solution 2:

I started a game with the hooligan personality, and sometimes my darkling puts on an England soccer shirt and urinates while dancing.

I will update the answer when I get a chance to play it with abdul, but it appears that it only affects jokes and dialog, nothing gameplay-wise.