A breakdown of Othorion, Katherine, and Nayana can be found in the Episode 11 show notes here. 

More information on the Solarum will be made available as the plot progresses. 

Othorion was arrested and sent to Revel's End on the crimes of assassination attempts on Katherine and Nayana via The Assassin's Guild. 

The party decided that Katherine and Nayana should jointly lead Solas, although Katherine has utilized Nayana's attacking of Othorion as leverage to usurp her power.