One scenario could be that they are studying together in the library. They start off bickering about a certain spell or potion, but then the mood shifts. James says something really sweet and sincere about Lily's intelligence. She blushes and then, suddenly, they share a quick, unexpected kiss among the stacks of books.
Another scenario might be at a Hogwarts party. There's music and dancing, and Lily and James are both having a great time. They end up dancing close together, and the atmosphere is so charged with their unspoken feelings. As the song ends, James takes Lily's hand, looks into her eyes, and they have their first kiss right there on the dance floor in front of all their friends.
One scenario could be that they are studying together in the library late at night. James accidentally drops a book and as they both reach for it, their hands touch, and there's this electric moment. They look into each other's eyes and then share their first kiss. Another could be during a Quidditch match. Lily is cheering for James from the stands, and after he wins, he flies down to her and kisses her in the excitement of the victory.
One interesting scenario could be that the kiss happens right after James has finally proven himself to Lily. Maybe he has just saved her from some sort of danger, like a dark wizard attack at Hogwarts. Lily, seeing James in a new light, is so overcome with gratitude and a newfound attraction that she impulsively kisses him. This would be a moment of realization for both of them, as James has been longing for Lily's affection for so long.
In some fanfictions, their first kiss might be described as a passionate outburst of long - suppressed feelings. Maybe it happens during a moment of great danger when they realize how much they truly care for each other. For example, after James saves Lily from a dark wizard's attack, the adrenaline and relief mix with their underlying love, and they just can't hold back any more, leading to that first, electric kiss.
A common scenario in fanfiction for their first kiss is that it occurs during a school event. It could be the Yule Ball. James asks Lily to dance, and they have a great time. As the night comes to an end, they walk outside to get some fresh air. The atmosphere is magical, with the stars twinkling above. James takes Lily's hand and tells her how special she is to him. Lily smiles and then James gently kisses her for the first time.
One interesting scenario could be their first meeting in a magical forest. The forest is filled with glittering fireflies and strange, beautiful plants. James might be a bit clumsy and say something silly at first, but Lily finds it endearing. They start to talk about their dreams for the wizarding world, and there's an instant connection between them.
There's usually a lot of nervousness. James is likely nervous as he's been longing for this moment. Lily too might be a bit jittery as she's finally allowing herself to be vulnerable with James. There's also a sense of excitement, like they are starting a new chapter in their relationship.
The kiss can be a turning point. It might make their relationship more serious. Before the kiss, they might have just been friends or had unspoken feelings. But after the kiss, they start to think about a future together. For example, they might start spending more time alone, going on secret dates around Hogwarts, like picnics by the lake.
James Potter was a bundle of nerves as he waited for Lily Evans outside the Three Broomsticks. He had combed his hair a dozen times and made sure his robes were spotless. When Lily finally arrived, her red hair seemed to shine even in the dim light of the pub. They started with a butterbeer each, and James stammered out a joke that made Lily laugh. As they talked, James found himself more and more drawn to her intelligence and kind heart. They ended the date by taking a stroll under the starry sky, and James knew this was just the beginning of something wonderful.
They could go for a walk around the Hogwarts Lake. James might show Lily the secret spots he knew around the lake, like the hidden alcove where he used to go to think. They might also see some magical creatures along the way. James could try to impress Lily by imitating the calls of the creatures.
One great fanfiction on this theme is 'The Marauders' Era: Lily's Perspective'. It delves deep into how Lily might have gradually fallen for James. It shows their interactions in Hogwarts in a very detailed and engaging way.