Both Eradicator and Decayr are In constant pain, Eradicator's blood is boiling to sustain his infinitely unstable and painful form (his blood needs to boil or he will cease to exist), Decayr is in pain because he is rotting on the molecular scale (but also heals right after it). Both are made with cosmic materials (Plasma blood for Eradicator and Dark matter for Decayr) Also the heatseeker is Eradicator's blood