User blog comment:Dispelling Mage/Omake: Lucy & Migi - Review/@comment-4449950-20150829072752/@comment-25395791-20150829082816

Good idea. ^^" Yeah. Figured that one out. Also, SPOILER follows:

When a parasite killed Shinichi's mother and took her over, it went for Shinichi and stabbed him in the heart. However, Migi managed to save the latter, but the consequences of that action were that parts of Migi entered Shinichi's bloodstream and irreversibly spread themselves within Shinichi, causing him to act differently (from what I understood) and which is most likely why Migi was, in fact, able to come back to him.