The two things MC pledged to do were protect Eliza and get revenge for his parents. In my mind those things take precident over what he wanted to be when he was 10, and what his parents wanted doesn't enter into it too much. His parents didn't want him to be an adventurer and if he could have asked them they probably would have told him to find Eliza and then take her and go back to the north where he came from and be a farmer. Whatever I did, I'd have Eliza next to me - unless it was something incredibly dangerous, and since she became a vampire, that's not much. If I could have I would have killed the Pirate twins, but in any case I certainly wouldn't bail on Eliza and run off to their rescue - I don't think even MC's parents would have encouraged him to do that.