Ever since the latest LW stories I've had the thinking that some of the elder dragons are misunderstood. We know Kralk was not intentionally as evil as he appeared, and was instead tormented. Jormag has offered and invitation for assistance, and wants to help Aurene. Can she be trusted? Absolutely not. Can she be a useful ally against the remaining elder dragons? Absolutely.
I think that with everything we know about the elder dragons, and how little we know about bubbles--kind of tell us about what kind of dragon bubbles might be. One that is patient, waiting, and manipulating. We know that when an elder dragon dies the other ones get more powerful, so presumably bubbles would have gotten a powerup from Mordremoth, Zhaitan, and Kralk. Bubbles absolutely COULD have showed itself to the world...and we know that the krait and largos fear it, but nobody on land knows about bubbles or even his/her name.
Primordius seems like he's possibly the most cunning of the dragons--but I would not be super surprised if bubbles managed to manipulate everything so far. I can reasonably see Primordius underestimating bubbles, while Jormag is trying to hedge her bets by forging a temporary alliance with Aurene.
Jormag might know its in her self interest to work with Aurene against the elder dragons--who are mostly hungry for each others power.
We might perceive Jormag as a bad dragon (reasonably too, considering the slaughter of Jora's keep) -- but Jormag might see herself as building a fortified army to....save the world?