"Loving your enemy" is actually much older than you'd expect: Just look at a https://en.wikipedia.org/wiki/Mistletoe .

It is a bilateral relationship actually.

There are trees full of them but they never drain their host tree till he dies no matter how many of them are on one specific tree. (Now explain that one...hehe)

And there are relatively specific breeds of small singing birds that build their nests into mistletoes preferably.