Age 0-7
Leyton and Luca were raised primary by their mother while their father was off doing whatever it was he was doing, and hiding from the ministry for acts committed during the first reign of terror under the Dark Lord. His father kept a close hand on everything that was happening, up until he got locked away in Azkaban the first time.
Age 8-11/12
During this time Leyton grew closer to his cousin Draco than to his own brother. Spending more time at the Malfoy Manor than his own time and being a growing boy he and his cousin got a little too close than Lucius would have liked and being that Leyton was the older Lucius held him responsible for the acts.
Every night that Leyton stayed at the Manor Lucius would drag him from bed after everyone else was asleep. Thats when the beatings and torment would begin. The next day Leyton would have to pretend like everything was perfectly fine. Slowly his innocence was taken and he began to resent everything about the name of Malfoy. He became colder and more distant as time carried on, and the scars were well hidden, both mentally and physically.
Age 12 (summer after year 1 at Hogwarts)-16
Leyton unable to take the abuse any longer becomes volatile and hostile towards everyone around him. Pulling away from everyone he turns his back on Draco, not only because every time he looks at him he sees Lucius, but because he was afraid of what else could happen to him. Draco and Leyton become almost like strangers. Leyton's grades begin to suffer, and his mother not knowing what to do begins to give up on him as well.
Feeling alone he turns to alcohol the older he gets and at the age of 15 starts sleeping with basically any witch who is willing to try to dull the pain. His father gets locked back up after the raid on the ministry as well as Lucius and Leyton sees this as a chance to finally try to see Draco.
It backfires though the summer going into his seventh year and after one drunken night in August they hook up at the Leaky and Leyton realizes just how dangerous it is to let his cousin back in so he pretends that the night never happened.