Silver for going against the grain and actually disliking the player character. Though HGSS kinda throws that out the window in his post Elite Four encounters.
That is called character development. He also changed a little in gsc. Soo yeah.
I'm aware it's character development >_>
The change is more profound in the remakes. In HGSS he goes full "frienemy" status with the PC. In GSC, that doesn't seem to occur, despite acknowledging the PC's skill. I would have preferred it that way; Silver learns to treat his Pokemon with care (as hinted as his Golbat evolves into Crobat), but still just doesn't like the PC (or Lance).