Rick Riordan said this quote

The real story of the Fleece: there were these two children of Zeus, Cadmus and Europa, okay? They were about to get offered up as human sacrifices, when they prayed to Zeus to save them. So Zeus sent this magical flying ram with golden wool, which picked them up in Greece and carried them all the way to Colchis in Asia Minor. Well, actually it carried Cadmus. Europa fell off and died along the way, but that's not important.It was probably important to her.