The Stories of Ys Series by Amy Rae Durreson

Sjurd is convinced that Celyn of Ys is the most irritating man alive. It’s a good thing that Celyn is engaged to Sjurd’s brother, not him, because Sjurd loathes the brat, and it’s quite mutual. When an elopement and the threat of invasion force the two princes together, however, they have no choice but to marry and fake true love to keep their countries safe. Can warrior Sjurd and diplomat Celyn find any common ground?

Life is easy for young artist Heilyn, as he travels between the floating islands of Ys with nothing more urgent to worry about than what to paint next. Then he meets sad, serious Emyr and forms a new ambition. Before he leaves for the next island, Heilyn's going to make Emyr smile. But will a smile be enough? If he wants more, Heilyn will have to choose between his wandering ways and the man he's coming to love.