Nitpicking note : I don't think the Weasley twins just want to have fun. They are in Griffyndor, in the Order of the Phoenix, they fight the Death Eaters to the end, ... they want to have fun, but they also want others to have fun.
In the canon, sure. Their HPMOR characters are not nearly as nuanced.
r/HPMOR readers on heroic responsibility - not the OP, the comments. Holy snorkels this is good.