What if Manuel Komnenos had had no son (OTL's Alexios II) in 1169 and was left with Maria Porphyrogenita as his sole heir? Would she be able to rule on her own accord?
Thinking of doing a TL with a "Byzantine" equivalent of Tamar the Great of Georgia and have found Maria to be such an intriguing personage. Obviously she was the leader of the "anti-Latin" faction in Constantinople following her father's death in 1180 and led the plot against Maria Xene/The Protosebastos Alexios...she appears to have been ambitious, well educated and highly driven to rule.
She will obviously have to marry a suitable spouse to rule alongside her, who besides OTL's Renier-John of Montferrat would have been a good candidate? Would the Montferrat connection have strengthened her position with the aid of Renier and Conrad, the OTL Crusader?