Reciprocate

verb

1. To exchange two things, with both parties giving one thing and taking another thing.
2. To give something else in response (where the "thing" may also be abstract, a feeling or action) To make a reciprocal gift.

   "I gave them apples from my tree; they reciprocated with a pie and some apple jelly."

3. To move backwards and forwards, like a piston.

   "A reciprocating engine."

4. To counter, retort or retaliate.