I am a little thrown for stamina, I know it been said colossus does not need to eat or sleep, and people assume he can go on forever with out tiring, I not sure I agree, I mean he shown before to tire or revert back and so forth, he also has certain amount of damage or energy drain he has reverted back to human from? so if this is the cases that certain amount of energy is taken away he will revert back, does that also not mean that sooner or later he be force to revert to human form.