Written for challenge #108: Fast Forward
Jack didn't believe there was anything after death. Even after the incident at the House of the Dead, he didn't really believe. But Ianto knew differently.
Those who left the mortal world before their soulmates waited until their partner died, and they journeyed on together to whatever came next. Until that time came, they watched over their husbands, wives and/or lovers.
Ianto had had the misfortune of finding his soulmate in Jack Harkness. Which meant he was trapped in the netherworld, unable to go backwards or forwards. After a few centuries, he had taken it upon himself to try and make the transition from the mortal coil to this place as easy for the newcomers as possible – he greeted them, explained what had happened, and what would happen when their partner(s) died too.
This didn't stop him from watching Jack. He had seen Jack go through a horribly self-destructive phase just after he had died, and seen him become moral for a brief time during the so-called 'miracle'. And he had seen Jack try to move on. And it broke Ianto's heart each time Jack left someone because he wouldn't break the promise he had made to Ianto.
But Ianto could never be too upset, really. Because every few years, he would get yanked from wherever he was, all the way back to Cardiff, and he would get to spend a few hours standing by Jack's side, looking out over the bay. And as the sun set, he would reach out and touch Jack's cheek as he tied a red ribbon around the railings. And he would cry as Jack whispered 'happy birthday' to him, wishing he could say something back, wishing he could comfort Jack.