Manfryd inherited his lands and titles from Lord Walys Mooton, his brother, after Walys was burnt alive by Sunfyre, the dragon of King Aegon. Manfryd originally kept in line with his brother's support of Rhaenyra, and Maidenpool played host to King Daemon Targaryen and his paramour, the baseborn Nettles. After the betrayal of other baseborn dragonriders Rhaenyra ordered that Nettles and Ser Addam Velaryon be executed, and sent a message to Lord Manfryd informing him as such.
Lord Manfryd was disturbed as he did not want to break guest right by killing the girl under his roof, and also wanted to avoid the wrath of King Daemon. His councilors advised him to pretend never to have seen the letter, and his Maester, Norren, informed daemon and Nettles of the queen's decree.
Daemon and Nettles left Maidenpool the next day, thanking Lord Manfryd for his hospitality and informing him to tell Prince Aemond Targaryen that Daemon would be waiting for him at Harrenhal. Shortly after the two left Manfryd raised the standard of Aegon over Maidenpool, replacing the flag bearing the sigil of Rhaenyra. This almost brought the queen's wrath on House Mooton, but she lost power before she could unleash it.
After the war ended Lord Manfryd was one of the Seven Regents, but died in 134AC and was replaced by Ser Corwyn Corbray.