The Black Dog’s job was to sow distrust in the group, but I think several of you have it right. Chris/Grim needed to specify what he wanted stood down, especially since he’s the one who taught Declan to keep his shields up. Declan could see what Grim apparently missed or had forgotten, that the feds had backup guns & were reaching for them. Then Grim escalated the situation by attacking Declan, who only defended himself. I think the only reason Declan had for apologizing afterwards was he still, at some level, considered Chris to be older & wiser (the angel part doesn’t hurt either) & presumed he had somehow messed up.
However, Declan is getting wound up pretty tight & reading the two Compendiums, seems to be getting more & more aggressive & confrontational in nature.
He seems to have no issues with throwing power around lavishly anymore & I don’t think anyone but his aunt & Stacia have much leverage in restraining him either.
Of course, almost all those confrontational issues come from defending Stacia in one way or another.