Draco has been suffering from depression ever since the war, he blames himself for everything little thing, he also blames himself for not telling Harry how he truly felt towards him, before he started to date Ginny.
Harry is late to potions class and gets seated beside Malfoy for a potions project. Each pair has a specific potion they must brew that causes a different emotion. When Draco and Harry realize what emotion they got, things take a turn right into sexual.
(Will have smut)
(Unedited, has spelling errors)