Thanos is barely contained. All the Guardians know for sure is that he's a major player for the cosmic abstracts, so it's probably best to leave him alive until they better understand his role and the consequences of killing him. They don't have a lot of time to think, however, as it soon becomes apparant that things are brewing between the Fault and the Church of Universal Truth. Even scarier: the evil Magus, who has threatened our Universe time and a again, is but a minion of that from the other side.
