Soul Bond — Christine Price

Some bonds can't be broken by time. Or space. Or death.

When Captain Julian Gaspar captures an enemy spacecraft, he takes aboard a sapphire-eyed stranger who captures his heart. The powerful attraction that draws Julian to the mysterious Ellis is instant, undeniable, and throws Julian's well-ordered life into chaos.
The heat they generate burns as brightly and naturally as the stars -- until Ellis is stolen away by a merciless pirate who trades in lives. In a heartbeat, Ellis is gone, leaving Julian broken and haunted by his last, angry words to his lover.

After five years of searching, Julian is finally reunited with Ellis, only to find him dying, imprisoned by a strange, ring-bound enchantment that is slowly draining his soul. Removing the ring will mean his immediate death unless Julian can find a source of powerful, ancient magic. Older than the stars. Older than time…

Warning: Contains spaceships, explosions, spiteful aliens, not-so-spiteful aliens, sarcastic alien yentas, the occasional naughty word and plenty of steamy man sex.