The remains of the Western Roman state had been ruled since 476 by Odovacar, as supposed viceroy in the West to Eastern Emperor Zeno. The latter was uncomfortable with this arrangement, as Odovacar had presented him with a fait accompli. At the same time, in the mid 480s, Zeno was facing repeated invasions into Eastern Roman lands by the Ostrogoths under Theodoric. After the uprising against and defeat of the Huns in the 450s, the Ostrogoths had settled on the Byzantine side of the Danube en masse through foederati agreements by Byzantine Emperor Leo I. At his death in 474, they left their reservations based on hospitalitas, criss-crossing Thrace and the Balkans in search of food and in general warfare. By the late 470s, Theodoric had gained prominence as an Ostrogothic leader. Alternately supporting Leo II against rebels such as the general Illus and the Germanic-roman officer Theodoric Strabo, and revolting in search of food and better office in the Roman system, the Ostrogoths spent the greater part of the 480s raiding up and down the Balkans. At the same time, Odovacar in the West had heard of Zeno's plans to oust him, so launched a preemptive strike into Pannonia, the Western Balkans, hitting the Rugians hard. In 488, Zeno thus offered Theodoric the position of Master of Soldiers in Italy, in return for unseating Odovacar.
Tired of a seventeen-year trek through Byzantine lands, Theodoric agreed. Passing through Pannonia, he acquired Rugian and Gepid troops through 489, then moved into Northern Italy, attracting Burgundians and Visigoths to the fight. He quickly reduced Odovacar to Ravenna, which was put under siege until 493. Then, in a banquet called to signal reconciliation, Theodoric and his servants murdered their opponent.
Thus from 493, Theodoric established the first post-Roman kingdom in the West. By the 510s his lands included all of Italy, stretching past Milan in the north to the Alpine regions, where the kingdom abutted the Franks as well as the Burgundians in the northwest. Provence was also included in southeastern France, after Frankish defeats of the Visigoths in the region. Finally, Pannonian and Dalmatian lands along the Adriatic were incorporated into Ostrogothic dominions. Legally, he presented himself to Italian Latins as the Emperor Zeno's Master of Soldiers for the region, and maintained as thoroughly as possible Roman urban and rural administration, including the Senate. To the Germanics, however, he was a king. In effect, the system was dualistic: Roman law, practice, religion (Catholicism), taxes, and language for the indigenous Italians, as opposed to Germanic kingship, tribal Ostrogothic (as well as Rugian) law, Arianism, and military duties for the German newcomers, who were outnumbered by native Italians. The relationship between the two groups was based on the old hospitalitas model. Roman landowners were required to provide about one-third of their agricultural revenues. This "administrative dualism" was justified according the Roman legal convention that the military-- in this case the mostly Gothic Germans--was in legal, financial, and other matters, accountable to a different system from that of civilians--the natives in this case.
From 493 to the 520s, Theodoric made his rule popular and administrated Italy better than any predecessor back to the 410s. Though Arian, he respected the Catholic Church, which was currently in a sate of schism with Constantinople over doctrine. His military force was equal to all challenges of the day, and through marriage alliances with Vandals, Visigoths, and even Franks, he was able to fend off territorial challenges. He also sponsored building and restoration projects in Rome, Ravenna, and elsewhere, even reestablishing the grain and wine dole for the urban masses, after having turned Sicily into the grain producing area given the Vandals' control over North Africa. Theodoric also attracted capable Roman aristocrats as administrators, including Cassiodorus, Boethius, and Symmachus, who were invested with proper Roman titles (and offices of) Patrician, Consul, and Master of Offices, the chief civil administrative offices in Roman parlance. Basically, the division of labor, in Theodoric's mind was Goths as military and Italians as civil, so that a Germano- Roman harmony could continue.
Providing comparative security and a semblance of Roman continuity to the 510s, Theodoric's rule began to falter at this time. A) The German/Goth elements of the system did not quite fall into step with the spirit of their king's arrangements. For example, when they traveled to Ravenna on a yearly basis to receive financial bonuses as soldiers, Gothic units plundered native farms and villages along the way. B) Byzantine Emperors were increasingly displeased with what they considered Ostrogothic expansionism into the East. Anastasia had disliked Ostrogothic occupation of Sirmium in the Balkans in 504, as well as their 505 defeat of Bulgars along the Morava river. Restricted in resources, the Greeks did launch naval raids on Italian coasts in 508, and the Emperor recognized the Frankish King Clovis with an honorary consulship in 507, as at least a symbolic counterweight to Theodoric. In 518, Justin became Byzantine Emperor. A native Latin speaker born the Balkans, he was keen on reestablishing stronger ties with the Italian Roman aristocracy as well as the Catholic Church. D) A divide of increasing importance between Goths and Romans was based on religion. Though Christian, Goths were adherents of Arianism, considered heretical by the Western Catholic Church. At the beginning of Thoedoric's rule, this was not too important. He respected Catholic churches, and felt that Goths would remain Arian, as Italians would stay Catholic. At this time, there were no Catholic candidates for rule; Franks were still pagan, and the Eastern Emperor embraced Monophysitism, so the Church in Constantinople was in schism with that of Rome. By 518, the situation had changed. Between 496 and 506, Clovis had led his Franks into the Catholic form of Christianity, and his comparative savagery did not outweigh his conversion's significance in the eyes of Italy's Catholic clergy. Further, Justin of Constantinople was totally Orthodox in his beliefs, opening the way for Rome- Constantinople reconciliation and his reassertion of influence in the West.
From the 520s, Theodoric felt much more insecure in his rule, wedged in between a Catholic Barbarian to his north and an Orthodox Emperor to his east. In 519 direct Papacy-Byzantine relations were restored, and Justin elected to forbid Germans in his realm from backsliding into Arianism after converting to Catholicism. Around this time, Theodoric forbade Italians from bearing arms, and sent Pope John I to the Byzantine capital to secure toleration for resident Arians. Though he succeeded, the Pope was received too favorably in Constantinople and showed too much devotion to Imperial revival (he crowned Justin) for Theodoric's threatened tastes. Upon his return in 526, John I was detained in Ravenna, dying in custody. Certain Roman aristocrats, such as Boethius and Symmachus, were judged to be in treasonous communication with Constantinople, and were executed. And, while the new Pope, Felix IV (526-30) was more Arian-tolerant and diplomatic in his relations with Theodoric, the Roman clergy was quite pleased with the restored bond with the East. Feeling ever more pressured and without a real Germano-Roman melding, the King ordered Arian confiscation of all Catholic churches, but died on the day of the decree.