If there are only 2 coins in the world and they are valued at 100.00 and nobody sells for fiat at a cheaper price, there is no volatility.
There isn't such a world and, be honest to yourself, there will never be such a world.
Be honest, that is a lousy answer. This is what you say when you have no answer.
If your question starts "there are only 2 coins in the world", then that above was my answer.