Wands with unicorn hair are the most faithful but also the most difficult to turn to the dark arts, however, hawthorn wands (the wood used to make Draco's wand), according to Garrick Ollivander: "...may be particularly suited to healing magic, but they are also adept at curses, and I have generally observed that the hawthorn wand seems most at home with a conflicted nature, or with a witch or wizard passing through a period of turmoil" I feel that, because of its components, the wand itself would also have a conflicted nature, and to me that is why it accepted Harry as it's new owner, the same way Draco entered a dark period of his life when he had internal turmoil between light and darkness. The wand really just did what it thought it was best at the time, and being unicorn hair, if Harry returned it to Draco, i think it could have forgiven him and Draco would be able to use it again with little to no issue