How should you explain the concept of marriage to your kid?

Lesta unbuttoned his shirt without much care, and I hugged the pillow in his place because I got too excited. You know, the kind of excitement when we encounter something interesting?

He unbuttoned his shirt just enough for it to show his chest. There, above where his heart should be, was a mark, roughly as big as the brand of contract Natha put on the back of my hand the first time.

"Whoa..."

I stared at the mark in fascination. I thought it would be like a tattoo at first, but it was closer to the mark I had on my palm; the mark of Alveitya. It looked like blood veins, those blue and purple lines we could see in our wrists. But the color was deeper, darker, the lines spreading like blooming flowers.