The connection between the Byzantine empire and the Holy Roman Empire was obvious through the niece of John I Tzimiskes who married Otto II. Her name was Theophanu and according to the Saxon chronicler Bishop Thietmar of Merseburg, Theophanu duly arrived in Rome in grand style in 972, with a magnificent escort including Byzantine artists, architects and artisans, and bearing great treasure.
Otto II succeeded his father on 8 May 973. Theophanu accompanied her husband on all his journeys, and she is mentioned in ca. one quarter of the emperor’s formal documents, evidence of her privileged position, influence and interest in affairs of the empire. It is known that she was frequently at odds with her mother-in-law, Adelaide of Italy, which caused an estrangement between Otto II and Adelaide. According to Abbot Odilo of Cluny, Adelaide was very happy when “that Greek woman” died.
The Benedictine chronicler Alpert of Metz describes Theophanu as being an unpleasant and talkative woman. Theophanu was also criticized for her decadence, which manifested in her bathing once a day and introducing luxurious garments and jewelry into Germany. She is credited with introducing the fork to Western Europe – chronographers mention the astonishment she caused when she “used a golden double prong to bring food to her mouth” instead of using her hands as was the norm.” The theologian Peter Damian even asserts that Theophanu had a love affair with John Philagathos, a Greek monk who briefly reigned as Antipope John XVI.
Otto II died suddenly on 7 December 983 at the age of 28, probably from malaria. His three-year-old son, Otto III, had already been appointed King of the Romans during a diet held on Pentecost of that year at Verona. At Christmas, Theophanu had him crowned by the Mainz archbishop Willigis at Aachen Cathedral, with herself ruling as Empress Regent on his behalf. Upon the death of Emperor Otto II, Bishop Folcmar of Utrecht released his cousin, the Bavarian duke Henry the Quarrelsome from custody. Duke Henry allied with Archbishop Warin of Cologne and seized his nephew Otto III in spring 984, while Theophanu was still in Italy. Nevertheless he was forced to surrender the child to his mother, who was backed by Archbishop Willigis of Mainz and Bishop Hildebald of Worms.
Theophanu officially took over regency in May 985 and reigned the Holy Roman Empire until her death in 991, including the lands of Italy and Lotharingia. By her prudent policies, she also was able to conclude peace with Duke Henry’s former supporter Duke Mieszko I of Poland and to safeguard her minor son’s interests. Like the Byzantine empress regnants Irene of Athens (752–803) and Theodora (815–867), who also had ruled for their minor sons, she issued diplomas in her own name as imperator augustus, “Emperor”, the years of her reign counted from the accession of her husband in 972.
She died at Nijmegen and was buried in the Church of St. Pantaleon near her wittum in Cologne. The chronicler Thietmar eulogized her as follows: “Though [Theophanu] was of the weak sex she possessed moderation, trustworthiness, and good manners. In this way she protected with male vigilance the royal power for her son, friendly with all those who were honest, but with terrifying superiority against rebels.”
Because Otto III was still a child, his grandmother Adelaide of Italy took over the regency until Otto III became old enough to rule on his own. (link)
There was also a connection to the people in the north as Scandinavians began to travel to Constantinople during the years 970-980. They applied for serving the Byzantine emperor as bodyguards and mercenaries. During excavations of Viking graves in Scandinavia almost one hundred Miliaresion have been found from John I Tzimisces´ time.