First of all, I don't have a clue what Canticle for Leibowitz is...
Saint Isaac Edward Leibowitz was the founder of the order named after him. He was a scientist who was martyred simply because he was among the educated populus and thus represented Science over common knowledge.
He had been married but his wife Emily (often called Em or Emma and who had a gold tooth) died before he took orders. One of the few remaining pieces of literature we have that was directly written by him concerns a debt to 'Uncle' followed by the single word "Damn". The math has been checked and it seems correct so the exact meaning of the damnation is not known.
Aslan is not a Tame Lion