Is there a word for something done to you because you did it to someone else?

I don't know for sure, but it reminds me of Hammurabi's code from the Mesopotamian Empire. That's where the idea "An eye for an eye" comes from.

The great Code of Hammurabi is often said to have been based on the principle of “an eye for an eye, a tooth for a tooth,” as if this were some fundamental principle of justice, elaborated and applied to all cases.

Also see: Code of Hammurabi

Another instance being the, almost petty, expression 'tit-for-tat'. This expression is defined, by Google, as a noun and means: the infliction of an injury or insult in return for one that one has suffered, i.e. "as we struggled for those last two votes, the tit for tat continued."

Also, tit-for-tat can be used in a sentence, e,g, "I noticed she didn't send me a card - I think it was tit for tat because I forgot her birthday last year" https://dictionary.cambridge.org/dictionary/english/tit-for-tat

There may be additional discussion as to whether one shoud write the hyphenated 'tit-for-tat' or simply tit for tat.

One meaning of a "reciprocation" is "a return in kind or like value". However, I'm not sure you'll be satisfied with this, as it doesn't specifically signify that the initiating act caused harm to the person reciprocating it.

https://www.merriam-webster.com/dictionary/reciprocation

It is not easy to find one single word which can mean requital or retribution, but of a negative kind and inflicting the same pain. A more informal phrase which means exactly that is:

get even

to punish someone who has done something bad to you by doing something equally bad to that person (Cambridge)

e.g.

Don't get angry, get even. (Collins)

A formal phrase is retributive justice:

Retributive justice is a theory of punishment that when an offender breaks the law, justice requires that they suffer in return, and that the response to a crime is proportional to the offence. (Wikipedia)

Some might call it ...

Karma

The idea of karma originated in Indian religions such as Hinduism and Buddhism, but is also used in the West to mean that good deeds will be rewarded with good results, with the opposite for bad deeds. This assumption is captured in the popular saying “What goes around comes around” and in the much older proverb “As you sow, so shall you reap.”

As noted in Psychology Today, Americans often say:

What goes around comes around.

Both suggest a type of philosophy that indicates an unavoidable retribution for wrong past deeds...

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Comments are locked. These ideas are not exactly unique. It should not be necessary to post links and citations to such obvious ideas, but I did.. I will leave this up for a while, then maybe delete and vote to close for SWR issues.