Here's an excerpt from fairly early in the manga, shortly after Matoriv joins the party, he asks Roka why Avan is Like That, so Roka explains some of Avan's family history

And, if you will excuse the French because the English scanlation isn't nearly this far, this is a page from Avan's final confrontation with Hadlar, where he's rejecting Hadlar's offer to let him rule half the world and here specifically he's talking about how he didn't get so strong on his own, the bonds he's formed with

people have helped him grow

I have confirmed that that shot of little Avan looking up at his grandfather's portrait is the exact same art on both pages, except that in Avan's version, he's smiling.