"Cold is just my protective color" means that this person does not show his feelings and heart easily, but protects himself by showing arrogance and indifference to avoid being hurt or violated. This may be because he was hurt or cheated, or because he habitually kept calm and rational in order to better cope with various situations in life.
"Illness is my killer" is a humorous sentence, which shows that this person's real strength and killer are displayed in the face of difficulties and challenges. He will not be easily defeated by difficulties, but will try his best to solve the problem. This ability and determination is his real advantage and charm.
Generally speaking, this sentence conveys a positive attitude, that is, a person should protect himself and show his strength and ability when necessary, and don't be afraid of challenges and difficulties.