Jarvis first appeared in the Batman Word to the Wise review. He also carries a magic gun, similar to the one Linkara has. His is powered not by the soul of a sacrifice but the love between him and his wife.
When Linkara defeated him in the Marville #4 review he became acclimated to our universe and his original universe became poisonous to him. Linkara promised to help him return to his universe and he agreed to help Linkara into the meantime.