The Ratpack is Ignis’ little group of miscreants that they meet on the streets, and becomes their first real family. They originally start as just a group of dejected kids trying to make their way in the world, but ultimately find themselves growing in notoriety after working under their “benefactor.”
None of the names are their actual names, they were young kids when they formed their little group and it's likely none of them actually knew anyone’s real name.