Also when did Vaerys run away from Camp? you mentioned it was after SOM but you also said he went on the solo quest with Ashe. So maybe he saw Ashe fall into Tartarus (we can say was held back my Luke's Boar Men thingies) and went back to camp and told them what happened? And they assume she's dead?
In the original Underworld Kid series they presume her dead because she hasn't returned for months, but since Vaerys is here in the other series, maybe we can make it so that he went back to camp and told everyone Ashe fell into Tartarus, and they presume her dead and hold her funeral. But that's another thing.
Does Vaerys go back to Camp after he sees her fall, and then immediately run away before anyone sees that he's back? Or does he return to Camp and inform everyone "Yo, she dead." before he hits the road? And I don't think you wanna say he stays long enough to see Ashe return, because you mentioned he leaves after SOM, and the Solo Underworld quest already stretches out of the timeline of the original PJO SOM. Not to mention Ashe was in Tartarus for an entire month and a half. So because he went on the quest with Ashe, he's already slightly overdue to run away according to you. Unless you want to change his story? Totally up to you, but please clear that up. :)