Two people who act just like each other can't . . . they don't . . . they're not compatible. As a daughter of Aphrodite, Piper McLean knows for certain that when it comes to love opposites attract. She and Jason are together. Percy and Annabeth are. Leo and Calypso are. Frankly, (did you see what she did there?) the only couple on the Argo II who acted like each other were Hazel and Frank.
People, she knows, are each half of a heart — they need to find their other half to complete their soul. That was what Prometheus was thinking when he made both men and women, right? (She's not very sure — it, ironically, was never her best subject. She didn't care much for the theories of the study, but the myths) Men and women complete each other. And really, it doesn't even have to be men and women, if you take Nico and Will for an example. There just is that one person in the world who will complete somebody else.
But of course, more often than not, things happen; car accidents and over-drinking and abortion. A person's soul will still search for it's mate, but it won't find it. So it settles for the next best thing — another half-heart that's missing a piece.
Love is complicated, Piper has learned, but she knows the logic of it — or rather, the lack thereof. There's a reason Annabeth and the rest of Athena's kids don't get love.
They're logicians, mathematicians, scientists. To them, everything has to have a rational answer. Even a feeling like love. But love isn't rational — it's magic, not the Hecate kind, but the kind which you read about it fairy tales. The kind of love which you find in the inappropriate books you read under the covers when nobody is in the house anyways, just for the thrill of it.
Love can't be measured or weighed or tamed. It's a part of human nature, one created with Chaos in the beginning of time. Love isn't an emotion, it's a force of nature.
late night randomness, apologies for the bad quality