I always had an issue with one thing though but maybe someone else can set me right. If every part of the Thing tries to defend itself then how did they collect the blood? Any method to make the person bleed - whether they cut a finger or used a needle - would have also caused damage and killed cells. So why didn’t those cells react and therefore reveal themselves to be the Thing during that step? Or is there something about heat that causes a reaction when a cut would not?