He remained in Rome, commanding a group of soldiers after the emperor's return to Provence in 902, and was prominent in the overthrow of Antipope Christopher in January 904, whom he very likely ordered to be killed whilst in prison later that year.
Theophylact formed an alliance with Duke Alberic I of Spoleto, and with their combined backing, Pope Sergius III was elected in Christopher's place.
[2][3] Sometime between the end of Sergius III's pontificate and the start of John X's,[4] Theophylact was elected the head of Rome, under the centuries-old title of Roman consul by the city's nobility.
The charges of adultery against Theodora, the use of the term "harlot", and the presumption that she was using her "feminine wiles" to prostitute herself in order to influence her husband and appoint numerous lovers to important posts were used to tarnish the rule of Theophylact and his successors.
Modern historians[example needed] now instead use the term saeculum obscurum to describe the period when the papacy was under the direct control of the Roman nobility, in particular when it was under the domination of the family of Theophylact.