Adventure. Don’t overthink it.
Thundrhed is the embodiment of audacity if not good judgement. There’s no problem a greatsword can’t solve.
Cheer as Thundrhed battles evildoers, ancient monsters, villains and the obstinate, blood-and-thunder stupidity for which he and all barbarians are justly famous.
Marvel as he crosses the world in search of treasure, middling infamy, lush wenches and eldritch artefacts to admire once, then dump in a crate with all the other priceless crap he’s looted in his travels.
What more could you want? Maybe dragons; just a couple of little ones for flavour. And a damsel in distress.