The major risk associated with writing a call option is the movement of the potential movement of the market price of the underlying asset in a direction that is not favourable to the call writer. This can happen in one of the following ways.
When the call writer has written an options contract to sell an underlying asset and the market price at the time of the expiration of the contract (say ₹10 per share) ends up being higher than the strike price of the contract (say ₹8 per share), thereby leading to a loss for the call writer;
When the call writer has written an options contract to buy an underlying asset and the market price at the time of the expiration of the contract (say ₹10) is lower than the strike price of the contract (say ₹12), it causes the call writer a loss.