Black Family Fatherhood Headcanons for Father's Day:
-Walburga sends her father the exact same bottle of cognac for Father's Day every year.
-Every Sunday evening Orion would read his sons a story before bed - from Nature's Nobility: A Wizarding Genealogy. This tradition stopped when Sirius was around nine and had developed an allergy to sitting still long enough to listen.
-Cygnus's favourite child is Bellatrix, because her skill at 'masculine' pursuits such as hunting was the closest he'd get to being able to imagine having a son.
-Arcturus personally taught Orion to play chess, a tradition Orion carried on with his own sons. Although Orion forced them to learn the hard way and never let them win out of kindness, he never once snapped "Idiot boy" at them when they made mistakes whilst playing - unlike Arcturus.
-Lucretia has been 'ill' for the last seven consecutive Father's Days, in an effort at least one of the three-times-a-year pecks on the cheek her father expects of her (the other two being his birthday and Christmas).
-On his last Father's Day before his untimely demise, Regulus accidentally gave Orion the exact same gift voucher for Flourish & Blotts that his father had given him at Christmas. The day had snuck up on him and he'd been left without any alternative present. He'd had so much going on that he had completely overlooked the handwritten message on the back. Orion was too downcast about the day itself to point it out and cause even more awkwardness than there was already in the house.
-In a post-reconciliation no-war AU, Sirius insists on spending Father's Day doing 'bonding activities' with Orion and Regulus, except he delights in doing all the planning himself, resulting in the other two having to endure very Sirius-minded things such as camping or hiking.