After the Shattered World Crisis had begun, Sonic continued to show moments of feral behaviour: during the Knothole Freedom Fighters rescue efforts in Station Square, and again during his battle against E-106 Eta aboard the Egg Train. Uncle Chuck became increasingly concerned for his nephew, after determining through his and Professor Pickle's experiments that the purple gas exhibited corrupted mutagenic properties. Again, Sonic denied that anything was wrong.(StH: #257, #259)