- "I hate to drink alone. Can I have a sandwich with that?"
- ―Simon in Frasier's home
Simon is an obnoxious and boorish heavy drinker, layabout and general freeloader, Simon has a difficult relationship with his sister, largely because of Simon's uncouth and selfish nature. He sometimes calls her "Stilts", referring to how she was tall for her age when she was younger. He is greatly disliked by both Frasier and Niles, partly because of their class-conscious nature but also because when in Seattle he frequently stays with one of them, often taking unreasonable liberties with regard to their homes, possessions and alcohol supplies in the process. Conversely, he gets on quite well with Martin and, despite his many negative qualities, he also seems to be a favorite with their mother, and is quite a popular man who is very successful at attracting women.
Roz Doyle is quite taken with him (and he with her) at first, but she eventually catches on to his ways and rejects his advances. Simon views her as a sex object, yet always forgets her name. During the ninth season episodes in which he appears, he constantly calls her "Rose." Roz does not care enough at that point to even correct him.
Simon first appears in Dark Side of the Moon and appears again in seven more episodes, including the two-part episodes Something Borrowed, Someone Blue, And the Dish Ran Away With the Spoon, and Mother Load, as well as Part 1 of Goodnight, Seattle.
- Like the majority of the Moon family seen on the show, he does not share a Mancunian accent with Daphne: the Australian LaPaglia imitates a London 'cockney' accent. He does, on occasion, wear a Manchester United t-shirt, and lead football chants in praise of United.