I am starting a game this fall in my own world and because of the size of the group wanted to avoid including my own full fledged npc. I am, however, unable to have zero influence so I have decided that my own part of the party will be a story device without being a character that needs to role play to the extent of a player.
As a result, i have decided that I will have my "npc" be an ex-familiar. The idea being that in this world when a wizard's familiar meets an especially brutal or tragic end and the familiar is the sole witness, the familiar will not lose its sentience when its master dies. Instead, fate kicks in and the familiar is awakened, as per the spell, and seeks to avenge or right the wrong.
In this case the familiar was a viper. His wizard was brutally murdered by an evil wizard and is the only witness to this wizard's cruelty.
My question arises in the context of advancement and building the viper.
As i understand awaken, he gains 2 HD and all of it (including his previous HD) becomes magical beast rather than animal?
Assuming this is correct, id like to ask what you all would do for advancement. Would you suggest the viper being taking class levels (rogue probably) or would you feel continuing with magical beast HD would be the best approach?
Thanks, and i can help clarify anything I've missed.