The Sun and Winter

Ivor Morrow doesn't want to die young. 

In Teramil, where only the wealthy can afford care, he just doesn't have a choice. Impoverished and chronically ill, Ivor dreams of studying engineering and living to see thirty, and for any of that to happen, fate must twist itself into impossible shapes. He has never known fate to be flexible. But when Vernick Mallory, born centuries before Ivor, falls out of the sky on the wrong side of time, fate tempts Ivor with a life beyond the boundaries of a struggling body and a society fueled by greed.

For Vernick, their meeting is a terrible mistake. In the wake of a siege, Vernick steals a runestone to turn back time and save his husband from a bloody end, but he learns quickly that stolen magic misbehaves. He accidentally flings himself centuries ahead to Ivor's present where magic no longer exists, losing the runestone in his crash landing. Without it, he'll never get home. The search for that stone leads him to Ivor, and if they don't work together, the universe will kill them both: one with a relentless illness and the other with an unsurvivable grief.