[@TheWindel]
Shadow Shot isn't sure yet if he wants to join the Black Guild, so he probably won't go there yet. However, I left my last post with 3 possible options for interaction: 

1. He gets a PM from someone hiring him. If you want, you can make this person for example the Black King wanting some back-up in case hell broke lose (which it did). 
2. He takes a job from the task board. The task board I mentioned earlier could happen to have a job for Shadow Shot, which could again be from the Black King. 
3. He talks with someone in the Blue Guild. This could be your idea of the Blue King interacting with Shadow Shot.

[@Lucius Cypher]
As Shadow Shot hasn't decided yet if he wants to stay with the Blue Guild or the Black Guild, he probably won't attack the Black Guild for now. I mean, say he does indeed join the Black Guild, others might not like him because of the assault. He would probably stay behind instead. Also, if Shadow Shot were to be hired to help the Black Guild, he wouldn't shoot the Blue Guild either, as he isn't a traitor.