Line up a set of polyhedral dice. Use some old dice that are full of stories, use some new dice that've never been rolled. Tuck the d20 into a warm pocket. The dice in the line are all old friends. Think about their personalities, their lives, their friendships. What do they talk about? Say they words they are saying to each other. You can talk with them too! Move the dice to a new place, let them look around. Introduce the d20. Say "Hi friends, I'd like you all to meet someone new!" They are going to hit it off, I promise. Let the dice have small adventures for as long as you like. At some point tell them the d4 is sick. About a month of dice time later you will pick up all the dice and roll them. Whichever dice rolled lowest have died. You'll need to tell the survivors the sad news. Let them grieve. This is hard for everyone. Dispose of the deceased dice appropriately. Roll the dice again. Odd rolling dice stick around though it's never the same. Even rolling dice leave; abandon them around town as you think appropriate. They live without you now.