Before time was time, Jaami was the chief administrator of Heaven. Then Yves convinced the venerable angel to make way for the Metatron, During their tenure, Jaami helped heaven work as one, after sealing their own power and joining David’s ranks dissent was able to creep into heaven. This ultimately resulted in the betrayals of Lucifer, Ophis, and the Grigori. Recently Lawrence learned Jaami’s true identity, and after a particularly humiliating defeat he sought out the venerable Kyriotate and restored it’s full power.
The two have been thick as thieves since. They agree on everything, and slowly more of the Archangels are falling into line, assisting Jaami in gathering everything and everyone back together.
Note: This is a non-canon interpretation designed to allow for an Angelic antagonist – the cannonical version is a simple wordbound servitor of David.