His name was Marcelo when he was at an orphanage and lived there until 12.

He escaped the orphanage then at the suggestion of his trusted friend Francisco. Afterwards, he joined the terrorist group MOK. Isol is the sole surviving child among the children who joined the group at that time.

He tends to use unnecessarily cruel way of murdering. He is overly disinterested in learning about others as he hates unnecessarily growing intimate relationship with others.
From game called Black survival 