Brother Sol is a male Felis sapiens and a Cat Cleric in the old cat religion (worshippers of Cloister).
Sol was one of three cat priests who fled the Cat Fleet when the self-appointed living god and tyrant Rodon took over and outlawed the old ways.
After being sentenced to death by Rodon, he fled with Sister Luna and Sister Peanut in a shuttle to search for Cloister aboard Red Dwarf, the place of their birth, and plead with Cloister, actually Dave Lister, to free the cat race from oppression.
The Cat Clerics were unable to locate Red Dwarf, and eventually took refuge on Iron Star and set off a distress signal. They were then discovered by the boys from the Dwarf there. (The Promised Land)
interrogates brother Sol