Okay, here's my latest proposal. (Many thanks to Darkreaver for the brainstorming help.)
Devyn Barnay was a classmate of Erasma at the Academy. He was awkward and shy, making him a bit of a bully magnet. He was, however, a good student. So when Erasma began to have academic difficulties, she persuaded Devyn to tutor her. Since her own popularity was fading, they developed a personal bond as well, although it's possible that meant more to Devyn than to Erasma.
Therefore, it was devastating to Devyn when Erasma fell into her coma. Upon graduating, he left Vikaastea for good and wound up in Waterdeep. It was there that he was noticed by a spymaster, who saw promise in him and began to train him in art of spycraft and recommended him to the College of Whispers for training as a bard. Devyn became an accomplished performer and was able to use that to insinuate himself into social circles and tease sensitive information from people. His mentor showed him how to leverage the secrets he pried from people to sell either the information to others or his silence to the owners. The mentor kept a substantial share of the profits.
At some point, Devyn and his mentor had an insurmountable disagreement and the bard left Waterdeep to find another city in which to ply his trade on his own. He eventually assembled a troupe of accomplished performers, which he fronted and hired out to play at numerous private events hosted by wealthy and powerful people. He trained his troupe in the art of listening and they fed him leads, which he then used to get to the really good stuff. They would stay in a city long enough to get established and make some good money, then leave for the next city before things got hot. But recently, mistakes were made and he and his cohorts were forced to leave town in a hurry. So he decided that maybe it was safest to let things blow over by traveling back to his home town of Vikaastea.
He is pleasantly shocked to learn that Erasma is not only alive but apparently healthy and powerful again, and he's delighted to renew that old friendship that was, in many ways, the one that defined him as a young man. And he's likely harboring hopes of deepening the relationship beyond mere friendship.
Darkreaver and I were thinking it would be terrific if the dancers at the party were actually part of Devyn's troupe, there to listen and bring information back to him. And maybe he either knows who the spy they cast out of the party was working for, or offers to find out who he was working for.