Brother Baston was recruited by Father Raul Piestro from the same asylum as Father Antoine and Father Joshua where they were being experimented upon to be super-soldiers. While they were the only three to survive, Brother Baston was apparently the best subject, surpassing all of the tests given to him by Doctor Gerard and becoming the strongest of the three.
However, he seems to have trouble controlling this as he loses control and they must subdue him. From the experiments he gained heightened senses and super physical strength, presumably along with regeneration.
During Volume 16, he clashes with Novic and he flashes back to his time before the asylum. In his previous life, Baston used to work at an orphanage or at a care home for children and appeared to have a jolly nature.