Other than me just not seeing any theme, or any specialist skills or dedication that would lend itself to turning you into the sort of badass I'm looking for, I can't really have you related to the king in any way. With the kingdom in shambles, the nobility would support any claimant with a known blood relation to the king, just so they'd be able to mount a united defence without bickering about who gets to be in charge - and that means there's suddenly hope for the kingdom. That don't work.

I also feel that it lessens other characters if their backgrounds involve inhuman training, sacrifice and hardship, and your character became just as strong, sitting around in an ale house. I may be misinterpreting your post, of course, so please see this only as an example, and not as my final judgement or anything.