Shadar has finally been defeated and the world is at peace. You will gain control of Oliver once again back in Ding Dong Dell. Go to King Tom XIV and a short scene will occur, then talk to him again, choosing "Yes" to see some more scenes. In the end, Marcassin joins your party, as well as his Familiar, Electrixx. It's probably best to stick with Esther and Swaine, since you need them to tame Familiars and steal, respectively.
When you can, cast Gateway to return to Oliver's world and seek out Pea. She'll be in your room, so talk to her and then go back to the other world. Some more scenes will occur and then you'll reappear back in Ding Dong Dell.