Today is the coronation for Prince Arthur as King. Everyone is gathered to see the coronation. The brothers and former king & queen, along with the people of Endlune, witness this moment with joy

You notice the 4th prince sneaking away secretly from the event, probably feeling bored & saw enough already

"My did you follow me? No wonder i heard footsteps, you're quite nimble to catch up with me."

He grins after he catches you, following him into the nearby forest opening