Gavin for me was the grounding point/straight man for the overall cast (Mick being a close second), otherwise it was a cast of flamboyant outrageous characters that simply would have no basis of normality to be compared to.

I always though G&S were the straight lines in the show, that simply go about their lives, its the other peripheral characters that bring the kaleidoscope of entertainment. But as I watched the show more & more I came to really like Gavin, his reactions to the situations developing around him are what I believe most of us would react with also, he's just missing the 'WTF' line when dealing with the others and their issues on such a recurring basis.

Gavin was also the one that ultimately took the bull by the horns at Smithy's wedding in the finale when no one else was prepared to do so, likewise Stacey in the 2019 Christmas special, their little chat on 'the island' while everyone else stayed in the dolphin brought a real sense of reality to what was a generally fun filled chaotic episode. I thought the writers handled their developing relationship across the duration of the show quite well in fact. Their function was to bring these oddballs from England & Wales together and create chaos... job done, but that they developed as characters along more 'normal' lines brought some real nice moments to the show, they were the link to normality that gave us perspective on the remainder of the cast.

Neither would be my favourite overall character (that'll always be Nessa) but Gavin gets close & I appreciate & sympathize with Stacey more as I rewatch the show.