At first, Ianto found the thought of being immortal and living forever rather daunting. What if Jack got tired of him? What if he got tired of Jack? What if they wound up hating each other?
Eternity together was a scary thought, but eternity alone… That had been Jack’s fate until the Doctor intervened; as Ianto recalled, Jack hadn’t been happy at the prospect of watching everyone he cared about age and die. Forever.
Ianto needn’t have worried.
Not that it was always perfect, they had their fights, but the bond between them only grew stronger as the centuries passed.