If he was in Spain, the guards would not follow him. Unless he hires an assassin…
However, there were perils inherent to being a French member of royalty. Bernard often spoke of avoiding Spain altogether. If captured they would use him as a bargaining chip to gain concessions.
If this was France, then his Father would have him hunted down and enlist the help from his extended family. His options on where to go were limited, especially if his father put a price on his head. Still, finding him would be made more difficult if he was not recognised on sight.
Disclaimer: This excerpt from Man of War is currently in development. There may be typos, errors, omissions, inconsistencies and so forth.