Fall
With the seasons out of joint, spring was the biggest worry, but fall going missing caused the mortals concern too. Hermes remembered it too well—the end of a year's harvest marked by a full moon, the occasional feast before winter set in, and the leaves changing to vibrant reds, yellows, and oranges before falling from the trees.
Orpheus could scarcely imagine the latter now; with Persephone's quick departure it seemed barely a day before the leaves browned and wilted, sloughing off hibernating trees. He had attempted to draw it once, going off Hermes' recollections, but he was more poet than artist and he drew what could charitably be called a mess of warm colors.
Still, it was a decent effort, and Hermes had told him that while fall could be difficult, it was necessary in preparing for winter. A few extra months to stock up on food, to gather firewood, could make all the difference.
As he worked on his song to bring spring, Orpheus hoped it held a promise of fall to come again too.