What's the opposite of "retaliate"?

What would be a single word to mean: "to do something positive to someone because they have done or said something positive to you", when you want to return the favour with something equal or better.

I Googled it and I found some odd results like "forgive" and "sympathize".

Solution 1:

Reciprocate does it for me.

There is also requite. But this is much less common, and slightly archaic, and mainly only seen as a negative past participle in unrequited love. I wouldn't recommend it for general use.

Solution 2:

• "repay" (note: I disagree with you comment on MT_Head's answer that this is dominated by negative connotations. It is used both ways)

While it's not one word, I am fond of:

• "return the favor"

Solution 3:

"Reward", "recompense", "honor" (if you happen to be royalty!), "pay back" (although this can be used in both a positive and negative connotation.)