In the beginning, it’d been a way to distract Jack so he wouldn’t see what Ianto was hiding. But after months of being starved of human contact, Jack’s attention and open affection had been like a drug Ianto craved constantly.
After Lisa, they’d slowly rebuilt trust, until by the time Jack left with the Doctor, Ianto had known he was in love, though he never expected Jack to feel the same.
When Jack returned, something had changed. He needed Ianto as much as Ianto needed him; love grew strong.
From a shaky start, they built something that would last forever.