In the time Jack is coming from, Sentinels and Guides are extinct. He knew there was an uprising in their population during the 21st century but never thought about it much. Coming back from the Year That Never Was, he is in no way prepared to awake as a Sentinel. Meanwhile Ianto kept another large secrete from the team and it doesn’t help to build any trust between them, when Jack and Ianto discover they are compatible as Sentinel and Guide. But with Jack’s newest experiences and knowledge, missing trust is not the biggest obstacle between them.