i mean, the Varangian's job is to protect the Emperor, which the praetorians are also SUPPOSED to do. However the Praetorians are fairly notorious for consistently killing the emperor they're supposed to protect so they can make someone else they can probably control...or one of their own numbers. So our Varangian friend is in fact just doing her job, which in this case involves opening up a seat among the Praetorians.