User blog comment:Bigez620/"Moon Madness" Review/@comment-32402536-20131010122515/@comment-24028957-20131010192348

Probably because Mike had a good side and a bad side. Heather wasn't affected because the human mind is so complex. With an evil personality already set into Mike's brain, the moon harnessed that bit and TMO came out, more easily than making an entirely new personality for someone else.

Sorry its really long, but I think it answered your question.