Disclaimer: Harry Potter does not belong to me and I claim no ownership for anything other than my wandering mind.
Hedwig flew swiftly through the night, delivering mail at odd times had become habit by now. She also knew to only deliver her package if the person was alone, Hedwig did not understand why her master wanted no one to know about whom he wrote to but she did as he asked. Most of her master's friends did not write to him during the hot months and during the school year they had no reason to, so it was only when he wrote to this one person that she got to regularly deliver mail. She was glad that someone wrote to him during the hot months though he was so sad during these months and while her master had her, she could tell that he needed someone else besides just her.
So during the night she flew to the blonde boy and would deliver letters between them and continued to deliver them at night even while they were at the castle. Hedwig thought it odd that they fought in public and yet wrote to each other fairly often. But humans were odd creatures, even if her master and his blonde friend treated her properly with lots of treats, they were still odd.
As far as she could tell no one knew that they corresponded with each other. But she did not know why they kept it secret, though perhaps they hid it so that her master's friends would not be jealous. They often wanted all of her master's attention and could hardly stand it when he bestowed his attention to others. At least they knew not to try to steal his attention from her, a few bites and they knew to leave him alone when she was nearby. Of course she could understand their envy, her master was magnificent and anyone in their right mind would want him to smile at them or even just listen to them. But why then did they not write to him during the hot months?
Hedwig could see the blonde boy's home in the distance and focused upon his open window. Landing on a perch by the window she waited for him to take her master's letter. She would rest for the few moments it would take for him to read and respond to her master's letter. The blonde boy always had cool water waiting for her and gave her a few treats while she waited so she did not mind staying for a moment. Looking over at him Hedwig could see him already writing a reply to her master's letter. Perhaps their relationship was odd but Hedwig knew they cared for each other and why should she care if they decided to keep it secret. It meant that she had mail to deliver and more opportunities to receive treats for her speedy deliveries.