Quarentined Universes contain forces, beings, or rules that pose a threat to visiting loopers and/or Yggdrasil itself, and as such cannot be allowed to loop themselves or to interact with any previously existing loops. Such universes are usually isolated from the rest of the multiverse by firewalls, although these have broken down a few times, allowing other loopers in.
It is possible, but extremely rare, for the problem causing a Quarantined Loop to be quarantined to be sorted out by the Admins, allowing the universe to Loop normally. So far, Homestuck is the only Formerly Quarantined Loop.
Examples of Quarantined Loops:
- Uzumaki, due heavy viral infestation and psychological dangers. The quarantine was somehow breached once by Simon, the anchor of Gurenn Lagann. During this visit, he was corrupted, almost permanently.
- Saya No Uta, due to multiple destabilizing elements, including psychological trauma and the potential release of biological contaminants that transform entire populations into eldritch abominations.