Frankenstein references aside, the real name origin is kind of strange. Per Dr Pepper themselves:

Wade Morrison, the drug store owner, named it “Dr. Pepper” after Dr. Charles Pepper, a Virginia doctor who was the father of a girl Morrison was once in love with.

I think you mean Moby Dick’s monster

What you’re referring to as pepper is actually Dr/pepper

If it’s not sourced in Romania, then it’s only sparkling Frankenstein’s Monster.

This made me lol