fall of Joshua (Summaries)

Caina Intro Summary:

In Caina, Joshua sends a message to any Astartes who are nearby, saying that he is betraying his oath to the Emperor and begining his heresy on planet Earth.

The Eight Astartes captains were the Eight sections (Excluding the ninth which is the "Outcasts") of Joshua's old Legion "Brotherhood of Steel". The closest one to Joshua, Icarus, wants to save Joshua, who he refers to as "Father".

The part with the captain receiving the signal on the Outcast is just for tension. Meaning if the Outcast came first, they'll kill every human and bring Joshua with them as their new Legion leader.