I'm looking for a science fiction short story where an intelligent alien race sees humanity at an early stage and decides they're scary as fuck and better off dead, so they send a weapon to destroy them, but then after that humanity meets and helps another species and the intelligent race realized they're not so bad and then feel bad about sending a weapon.
>>7997210
This?
>http://www.creepypasta.com/the-gift-of-mercy/