The facts contained in the plot of the Mousetrap suggest that Horatio's position in Elsinore is too high for a mere guest. He is close to the King who charges him to be with Ophelia after the madness manifestation, and 'wait on' Hamlet after the brawl with Laertes in Ophelia's grave.
In both plots, this character is referred to as Horatio. It is obvious that this ancient Roman name is a scenic one, and that in 'reality' Horatio must possess with a different name. That name is mentioned once in the text, it is Claudio (i.e., the younger Claudius). Therefore, Horatio is a son to the King bearing in the inner drama the scenic name of Claudius. To be exact, to king Hamlet. That explains Horatio's high position in the castle. So, prince Hamlet and Horatio-Claudio are half-brothers (cp. a similar case of Edgar and Edmund in King Lear).
Unfortunately, numerous editors of Hamlet do not include the name Claudio into the Dramatis Personae though it is mentioned in the main body of Q2 and F1 texts. On the other hand, the name 'king Claudius' has never been mentioned in the main body of either Q1 or Q2 or F1. The very first time Shakespeare introduced it was Q2 where it is mentioned twice only in the supplementary text to the inner drama. In F1, that number was reduced to a single case. Both names (Claudius and Claudio) were first mentioned in the same text of Q2.
Unlike prince Hamlet who was born to a king and was a son of the jointress thus being a legitimate claimant to the throne, Horatio had no chances to inherit the throne because he was born before his father Hamlet married Gertrude and became king.
Chapter IV: The Mousetrap for the Narrator of W. Shakespeare's Hamlet
Copyright © Alfred Barkov 2000, 2003