Around 520 to secure the succession of his youngest son Khosrow, whose position was threatened by rival brothers and the Mazdakite sect, and to improve his relationship with the Byzantine emperor Justin I, Kavad proposed that he adopt Khosrow.
This proposal was greeted initially with enthusiasm by the Byzantine emperor and his nephew, Justinian.
However, Justinian's quaestor, Proclus, opposed the move concerned over the possibility that Khosrow might attempt to take over the Byzantine throne.
The Byzantines made a counter-proposal to adopt Khosrow not as a Roman but as a barbarian.
In the end the negotiations did not reach a consensus.
Khosrow reportedly felt insulted by the Byzantines, and his attitude towards them deteriorated.

Mahbod, who with Siyawush, had acted as the diplomats in the negotiations accused him of purposely sabotaging them.
Further accusations were made against Siyawush, which included his reverence for new deities, and having his dead wife buried, a violation of Iranian law.
Siyawush was thus most likely a Mazdakite, the religious sect that Kavad had originally, but now no longer, supported.
Although Siyawush was a close friend of Kavad and had helped him escape imprisonment, Kavad did not try to prevent his execution.
Seemingly his purpose was to restrict Siyawush's immense authority as the head of the Sasanian army, a post which was disliked by the other nobles.
Siyawush was executed, and his office was abolished.
Despite the breakdown of the negotiations, it was not until 530 that full-scale warfare on the main western frontier broke out.
In the intervening years, the two sides preferred waging war by proxy, through Arab allies in the south and Huns in the north.
Around 520 to secure the succession of his youngest son Khosrow, whose position was threatened by rival brothers and the Mazdakite sect, and to improve his relationship with the Byzantine emperor Justin I, Kavad proposed that he adopt Khosrow. This proposal was greeted initially with enthusiasm by the Byzantine emperor and his nephew, Justinian. However, Justinian's quaestor, Proclus, opposed the move concerned over the possibility that Khosrow might attempt to take over the Byzantine throne. The Byzantines made a counter-proposal to adopt Khosrow not as a Roman but as a barbarian. In the end the negotiations did not reach a consensus. Khosrow reportedly felt insulted by the Byzantines, and his attitude towards them deteriorated.
Mahbod, who with Siyawush, had acted as the diplomats in the negotiations accused him of purposely sabotaging them. Further accusations were made against Siyawush, which included his reverence for new deities, and having his dead wife buried, a violation of Iranian law. Siyawush was thus most likely a Mazdakite, the religious sect that Kavad had originally, but now no longer, supported. Although Siyawush was a close friend of Kavad and had helped him escape imprisonment, Kavad did not try to prevent his execution. Seemingly his purpose was to restrict Siyawush's immense authority as the head of the Sasanian army, a post which was disliked by the other nobles. Siyawush was executed, and his office was abolished. Despite the breakdown of the negotiations, it was not until 530 that full-scale warfare on the main western frontier broke out. In the intervening years, the two sides preferred waging war by proxy, through Arab allies in the south and Huns in the north.
Kavad I