1. Conditional antagonism
[Nouns] retaliation, reprisal, retort; counterstroke, counterblast, counterplot, counterproject; retribution, lex talionis; reciprocation (reciprocity) [more].
tit for tat, give and take, blow for blow, quid pro quo, a Roland for an Oliver, measure for measure, diamond cut diamond, the biter bit, a game at which two can play; reproof valiant, retort courteous.
[Verbs] retaliate, retort, turn upon; pay, pay off, pay back; pay in one's own coin, pay in the same coin; cap; reciprocate [more]; turn the tables upon, return the compliment; give a quid pro quo, give as much as one takes, give as good as one gets; give and take, exchange fisticuffs; be quits, be even with; pay off old scores.
serve one right, be hoist on one's own petard, throw a stone in one's own garden, catch a Tartar.