Who is LLM?
22 July 2025
It’s become a common habit for developers to give Large Language Models (LLMs) a persona
when working with them. The first time I ran into this was my colleague Birgitta
characterizing her LLM as a stubborn donkey (called “Dusty”). She picked it because it had the
traits of:
- eager to help
- stubborn
- very well-read, but inexperienced (for Dungeons and Dragons fans:
high intelligence, low wisdom)- won’t admit when it doesn’t “know” something
I also like Kent Beck’s notion of using the persona of a Genie. When you
rub a lamp, the genie does what you tell it to do. But perhaps not quite in
the way you would have wished. The persona perfectly captures the mix of
great power, eagerness to help, and an almost pathological ability to
undermine whatever help it’s supposedly trying to give you.
The genie seems to assume that its planetary-sized brain is capable of
handling any amount of complexity, so it needn’t ever reduce complexity.
It’s right until it isn’t.
Kent also suggested another great persona in an off-hand comment liking
the experience of invoking it to using a slot
machine. Sometimes you get a fantastic result, often you get
dreck, and the distribution between the two seems random. It’s almost as if
the LLM is using the same addictive algorithms designed by casinos to keep
folks playing the slots. Or indeed the behavior of an abusive partner.
As I listen to those who use LLMs a lot, a common story is that we
have to invest significant effort to learn how to use them well. Hitting the
jackpot makes them seem like they are easy to use, but that’s a mirage,
which can skew our expectations of the technology, leading to
frustration.
A persona that’s been increasingly suggesting itself to me recently is
that of Uriah Heep – a character in Charles Dickens’s novel “David Copperfield”1 Heep is infuriatingly
obsequious, constantly stressing how “umble” he is and how he serves only to
do his betters’ bidding.
1: Dickens is fantastic at creating memorable characters, so
Heep is one of many from that book I remember well, even though I last read the
book as a teenager. Skimming through the book to find some suitable
quotations, I was reminded of how good a writer he was. In particular I was
struck by how many of the scenes I remembered, even occasional sentences
struck me as familiar even though it’s been decades since I last read them.
‘Oh, thank you, Master Copperfield,’ said Uriah Heep, ‘for that remark!
It is so true! Umble as I am, I know it is so true! Oh, thank you, Master
Copperfield!’
But he is full of malice: manipulating, and
essentially controlling those people he “serves”.
‘Uriah,’ she replied, after a moment’s hesitation, ‘has made himself
indispensable to papa. He is subtle and watchful. He has mastered papa’s
weaknesses, fostered them, and taken advantage of them, until–to say all
that I mean in a word, Trotwood,–until papa is afraid of him.’
Source: Martin Fowler.
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