Ready for the most annoying cheat answer?
Erring.
That's why the comic is called Errant! Because a Knight Errant is a knight who goes on a quest, but to be errant, or to err, means to go astray, become lost or to be, literally or metaphorically, in a place you're not supposed or expected to be or making mistakes. As the saying goes: "To err is human". Errant is basically about people making bad decisions or mistakes and going on journeys or wanderings that change them.