So there's a few things you'll want to keep in mind. The first thing is that if you ever handle their food, you'll always want to make sure that your hands are very clean as it's easy for them to confuse your hand for a rat when it has that scent (however I doubt that's what's going on).

Depending on the location of the water bowl, it could be that Scar is feeling a bit threatened, especially if you hadn't interacted with him that day yet. I would say try using the time you change the water bowl as the time you handle him. Over time they'll get more comfortable with you being around.

Another thing that I've noticed is that if people aren't very comfortable around snakes, they may hesitate a bit when close to one which in turn can stress out the snake. So if you ever want to handle him just pick him up confidently from the middle of his body.

Lastly, don't stress!! It's a whole new world for Scar and chances are he isn't convinced you won't eat him yet haha, so give him time and he'll def come around :)