Hamlet turns on the king and stabs him then forces the poisoned wine down his throat. Horatio, I am dead. I can't live without my buddy. Let me drink the last of the poison, says Horatio. What a pal.
Someone has to stay behind to tell the tale.
Enter Fortinbras back from Poland. But guess what. In come the English ambassadors to let Claudius know Roz and Guild are dead. THUD 5 and THUD 6. Do you notice how all this has worked out for Fortinbras.