James Potter had grown up showered to the brim with love from his parents. It was no surprise he ended up with lots of leftover love to give.
He met the first person he decided to love on the Hogwarts Express. The boy was an arrogant, self-absorbed prat who only wanted a little bit of love. He had aristocratic features and grey eyes he would never forget, not for the rest of his short life. If there was anyone in his time at Hogwarts James Potter loved more than himself, it was Sirius Black.
James meets Lily Evan next in a carriage on the Hogwarts Express. She is sitting with a greasy-haired, long-nosed boy and James Potter thinks she must be the most beautiful girl in the world. She has long, auburn hair and eyes like emeralds. He hopes one day their children will have his eyes, but it seemed unlikely as she flounced off from their carriage, taking the greasy-haired boy with her. James would pine after her for years until she decided to give him a chance. Things progress quickly after that and soon James is holding a bundle in his arms, a baby with his mother's eyes, who would go on to have his father's horrendous eyesight.
Peter Pettigrew comes next, pudgy and sweet with a heart of gold. He comes into the carriage a little self-consciously leading a sandy brown-haired boy in with him. Peter, who would be the fourth marauder, the forgotten one, Peter who would grow towards hate, Peter who had been the very best of all of them at Defense Against the Dark Arts. James Potter had loved Peter, had adored that sweet boy. He never told anyone but he thinks to himself that perhaps he had loved Peter first out of the four of them. Out of all the people in the world, James Potter's last thought had been of Peter Pettigrew, wondering what Voldermort had to have done to him to get Peter to reveal the location of the house because he knew that Peter would not have betrayed him. Not Peter, the sweet boy who on the first day on the Express, had used all of his pocket money to buy out the Trolley Witch and had shoved chocolate into Remus Lupin’s face when he refused.
Remus. Oh, Remus. James would’ve done anything for Remus if only he had asked. He remembers seeing the scars, the thin frame, and his kind brown eyes. Remembers the shocked look on his face when Peter had shoved chocolate at him, he remembers the full moons and pranks and talks that came later. Most of all James Potter remembers the way Remus Lupin looked at Sirius Black, full of love. James had looked at Sirius with love too, but never in the way Remus had. It wasn't until the summer before their sixth year that he had realised and he cursed himself for being so stupid. James Potter remembers the day Remus had cried to him, had said that no one wanted a werewolf, but James always wanted his werewolf. He always wanted his Moony. Sirius had wanted Moony and so had Peter.
It’s in his fourth year that James starts loving Marlene. She had joined the quidditch team as a beater and was a real slave driver when it came to practice. James knew that she hid behind a mask of cockiness because he had seen it in his Sirius. James misses Marlene sometimes, even when he can see on the map that she’s right there in the common room or in the library. He doesn't know why he misses her but perhaps it's because he didn't start loving her until fourth year, when he had loved everyone else for longer. Marlene deserved love, deserved it all and that was why he had kept quiet when he spotted her name and Dorcas Meadowes on the map, alone together in a quiet potions classroom.
Mary Macdonald is a muggle born in a world full of prejudice. James finds her alone in a corridor, the contents of her bag strewn about her, ink staining everything. She is crying into her knees and James sits down beside her and doesn't say a word. Time passes and that's what they do, sit quietly next to each other, just so that for a moment, neither of them feels alone in the world. It's shameful that James feels alone when he is surrounded by his people day and night, but Mary understands.
In a way, James loves Regulus Black too. He sees the way Regulus’s eyes flutter down when he looks at them, sitting at the Gryffindor table. He notices the way sometimes Regulus will appear in the hallways walking past them sneering when James knows his class is on the other side of the school. James wonders what love is when he thinks of Regulus, but god knows that boy needs the tiniest bit of love.
James Potter gave all of his love, the same way his parents had to him, and then eventually to Sirius and Remus and Peter and Lily and everyone. That is why Remus Lupin blinks when he sees Harry Potter on the Hogwarts Express, scarily like his father, and yet so desperate for love. Because Remus knows that James would have given everything to Harry, had loved him with every fiber of his being until his life was cut short. Remus doesn't know much about death but he likes to think that James is watching Harry, loving him even in death.