Twice a year Albus Dumbledore apparates to the village of Godrick's Hollow. Once on the anniversary of his mother's death and once on the anniversary of his sister's, Ariane. He goes in the evening, as night begins to shade the air and after dinner in the Great Hall. When he won't be missed.
Twice a year he goes to the graveyard behind the village church and stands beside their grave.
Each time he finds it freshly tended. There is always a fresh remembrance of flowers on the grave, laid earlier in the day. Gladioli for his mother’s anniversary and a posy of wildflowers for Ariane’s. Albus knows that they are from Aberforth just as he knows that it is Aberforth who tends the grave. He knows this because one year he spend the day under a disillusionment charm, watching him.
It hurts, that reminder of all that he hurt with his folly. He likes to think that it is wisdom which cautions him not to intrude on Aberfoth's part of the day. He takes the pain of that twice-yearly reminder as a penance for the irreparable harm he caused and as a reminder that he can't be trusted with dreams of power.
He conjures his own offering of flowers and sits beside the grave in whatever weather the day provides. There he contemplates his mistakes until it is time to return to his office and his duties.
Twice a year Aberforth returns to where he buried his mother and his precious little sister. He spends the morning tidying their shared grave. He brings their favourite flowers from his garden and spends time remembering their happy times. He speaks of the things he has seen or heard that he thinks would interest or amuse them.
These days are his to choose and what he chooses is to celebrate the good things. Despite that there is a part of him that can't help resenting his brother's repeated absence. Against his will the memories of old betrayals intrude, like the gathering of distant storm clouds. It feeds into his bitter anger against his older brother who left their family in ashes to pursue his great ambitions.