User blog comment:FairyRaven/Fairy Tail Chapter 366: 1000 Souls, Review and Commentary/@comment-92.37.55.98-20140109154110/@comment-7418318-20140110091440

A bit more specific.

Good child fights against evil father without knowing their relation, then in the middle of the fighter mr. evil goes "I am your father", followed by screaming or whining on the hero's part.

That's what I'd call pulling a Vader.

Much better for Silver to defeat Gray and once pants-man wakes up in a cell and asks why he wasn't killed Silver says something like "I just couldn't get myself to kill my own son after all." Even better yet not have them related at all... but that has become unlikely :(