A/N: This has mentions of self-harm and suicide, PTSD, cousincest, etc. If any of this disturbs or triggers you, please do not continue.
Disclaimer: I do not own the world of Harry Potter, nor its characters. It all belongs to the wonderful J.K Rowling.
This is for the Fanfiction Terminology Challenge - my terminology was 'cousincest'. So, here we go!
Lucy was nearly never impressed by James. Loud, annoying James Sirius Potter, her cousin, who was the last kind of person she wanted to be near. During Quidditch games he'd stand up on his broomstick and yell out who he was dating, brag about his parentage, and the Ravenclaw girl would sit in the crowd, scowling, wondering why she ever bothered to come. And then she would catch Al's eye, and see the boy try to ignore her, burying his head in a book to drown out his brother. James never noticed, nor cared about Al. She knew why - she was clever, a cleverer girl than most, and knew that the Potters were breaking. Ginny had walked out several times, Harry was losing himself to the throes of PTSD. James thrived on attention and love, and would do louder, more outrageous stunts every time to make sure the attention of his teachers, peers and family stayed on him. Albus buried himself in books, and hid from the other Potters, finding refuge in the library, or even sometimes by talking to Lucy. Lily was locked at home with Harry, and didn't really cope - she was a brick wall, standing tall through the hurricanes of emotions that hit her family.
Lucy didn't care for James' wild stunts. Her eyes were always on Al, the younger Potter boy.
Fourth year, Al's second. He drew into himself more than ever, and Lucy felt the need to comfort him. Everybody, it seemed, was too wrapped up in their own lives to notice Al. Only twelve, but the fourteen year old's eyes were never lead away from his scars. And when she would be about to talk to him about it, his brother would burst into wherever they were, with a magically amplified voice (not that he needed it), trying to sell his friendship like a salesman on the radio would a broomstick. It never worked - Lucy would shout herself red in the face until he left. But by then Albus would've slipped away into the shadows - her plans never, ever worked.
Fifth year, Lily was finally at school. She was Al, but different - Albus slid away, Lily didn't. Lily threw herself in the opposite direction to everyone else, refusing to have any contact with any of her cousins or her siblings. She made herself a reputation Lucy heard whispers of. Not good whispers.
But what would one expect? She'd been living with Teddy for a year, and before that, a mentally unstable father. James, however much he would try to shove himself into Lucy's line of vision, would never get there - it was always Lily and Albus she couldn't see past. As much as knots in her stomach were formed, she could not help staring - staring at her own flesh and blood, staring at Lily and Albus. And somewhere, her mind acknowledged the fact that maybe her feelings weren't exactly cousinly for Albus, and her obsession with him was a little outside of nature's laws. And the way she tried to dig, to try to get into Lily's mind - it was pure insanity. Lily was there, but never a distraction from Albus.
And it drove her insane, trying, failing, drowning in her need to understand Albus. He didn't fit anything - he didn't fit constraints of annoying or bookish or loud or depressed - every time he'd almost slip into a box, he'd catapult himself as far away from that as he could. He was thirteen, but his soul defied that. And it almost killed Lucy.
And sixth year - sixth year - she couldn't even yet drink, and she found herself in a little white room, one of the brothers lying on a bed, so still - he'd killed himself. And she found herself surprisingly, so surprisingly upset that she threw herself into the other's arms and they kissed so hard Lucy forgot her name. The boy lying on the bed had brown eyes, and the boy whose pure lips she'd kissed had green. And the little redhead came in, her brother was dead, dead and empty, not that they'd ever been close. And she walked in and saw her cousins fucking, in a hospital room, and she left, left, left, and they never talked again. Because cousins like that in a hospital room, next to a corpse.
And she never really got to talk to Albus after that, never found out why he did those things. And that killed her, it killed her that she'd burned her curiousity out in a moment of pure lust. It literally killed her, though on her gravestone it said stress. Stress, stress, stress. If the stress of a curiousity since you were twelve can kill you. If the stress of fucking your cousin can kill you.