|rom a 14th century Welsh Book of Hours,|
this is thought to depict Maximus [link]
He did things that did not sit well with his constituents, however. He is believed to be the first person to order execution for heresy when he executed Priscillian and six followers.* We are so used to thinking of the Middle Ages killing heretics that we would be surprised to know that this wasn't always common. In this case, St. Martin of Tours (mentioned here) tried to prevent it. On the other hand, when Maximus tried to censure Christians for burning down a synagogue, Bishop Ambrose of Milan condemned Maximus' decision.
Maximus also pushed his luck by driving out Valentinian II, who later, with the help of Eastern Emperor Theodosius I, returned and attacked Maximus, defeating him in 388 at the Battle of the Save (near modern Croatia). Maximus surrendered to his enemies at Aquileia; despite pleading for mercy, he was executed.
Maximus had family, and although we are not certain what became of all of them, we have some ideas, and legend offers another. His son, Flavius Victor, was strangled. His wife sought counsel from St. Martin, but we know nothing of her after that; we don't even know her name, although a popular Welsh legend calls her Elen. Maximus had a mother and daughters who were spared. One of his daughters, Sevira, is named on the Pillar of Eliseg as a wife of Vortigern. (The pillar was erected centuries after Vortigern, so we cannot be certain of the accuracy of the data.)
Later historians did not forget the story of a warrior starting in Britain and conquering Rome. They embraced him, and wove him into England's greatest legend. Accordingly, one of his grandsons was Flavius Ambrosius Aurelius, who had a son, Ambrosius Aurelianus. Depending on which ancient historian or modern author you pick, Ambrosius is either the uncle of King Arthur or is the figure on whom King Arthur is based.
*"Priscillianism" will be covered in the near future.