whena rider dies, his/her dragon dies too, but surikkan's old rider was killed by morzan. why is he still alive?

but my friend you forgot something this something is in the movie yes if a rider dies his/her dragon dies but in the book it is not true book never accepts this idea be couse of this shurikan is alive and shurikan was connected to galbatorix by using dark magic ı remember like this

A dragon does not die when his rider dies. The dragon has a good chance of going crazy because of the loss of the rider (and vice versa. A rider may go crazy if his dragon died. Brom went crazy for some time) but they won´t die.