The Exile Arc kicked off when a new member of the server, Ranboo, joined. Ranboo had been goofing around with Tommy and both decided to burn down and grief George's house. Dream being George's very close friend was not happy with this at all, and with Tubbo being the new leader of L'amanburg he had demanded that something be done. Over the course of a couple days Dream was like a gnat in Tubbo's ear trying to get him to betray Tommy. This eventually did happen when Tubbo exiled Tommy from L'amanburg, and he couldn't walk on any of the grounds of the SMP that had already been discovered. Dream took Tommy far away and would visit him every week, making sure he stayed put. Tommy's lore from they're got pretty dark diving into topics that were pretty serious. Eventually he started to wake and realize that he could just run away while Dream was gone. So, he did just that. On his journey away from exile, he discovered a house in one of the snow biomes of the server. This ended up being Technoblade's house. From here Techno would provide for Tommy until one day he returned to L'amanburg to confront Tubbo. In their altercation Tubbo gave Dream one of Tommy's discs. Somehow Tommy also ended up turning on Technoblade and becoming friends with Tubbo once more. This is what kicked off the Doomsday War.