The client liked that idea. They asked me to turn the little saliva guy into a superhero and refine the design for both. Also, they changed the names to Swish and Spit:
The final request from the client was that both characters always be smiling, to show their teeth. Here’s the final art. The project is on hold for now but the client has given me permission to share the work I did. Once it launches I will try to add a link to the final campaign.