modeling for characters
In the acknowledgements of comic book it is written :

"thanks to the people who modeled for characters in the book: Tamsey Glaser, Katherine Gilbert, and my most frequent subject, Paul Sizer."

Does it mean "these artists have designed and drawn the characters of the book" or "they are models who have posed instead of the characters and the author has drawn them"?

Question

modeling for characters
In the acknowledgements of  comic book it is written :

"thanks to the people who modeled for characters in the book: Tamsey Glaser, Katherine Gilbert, and my most frequent subject, Paul Sizer."

Does it mean "these artists have designed and drawn the characters of the book" or "they are models who have posed instead of the characters and the author has drawn them"?

Answer

Considering that he says 'and my most frequent subject, Paul Sizer.'  I would most likely say that it means 'they are models who have posed instead of the characters, and the author has drawn them.'

The clue is the word 'subject'