One interesting plotline could be Kankuro falling in love with a foreign ninja. Their different cultures create a lot of misunderstandings at first, but as they train together and face challenges, they gradually fall for each other. For example, she might not understand the significance of his puppet - making skills at first, but as she sees how it helps in battles, she begins to respect and admire him more.
One common character paired with Kankuro is Temari. Since they are siblings, some fanfictions might explore a different kind of relationship that blurs the line between family and romantic love in a very unique and complex way. However, this is often a more edgy and controversial take on their relationship.
One plot could be that Kankuro falls for a healer in the village. She mends his wounds after a battle. He is attracted to her gentle nature. They spend time together as she teaches him about herbs and he shows her his puppets. Their relationship blossoms from there.
Perhaps Kankuro meets a fellow puppeteer. They start competing with each other at first, trying to outdo one another in puppet - making and shows. But during this process, they realize they have a lot in common. Their shared passion for puppetry leads to mutual admiration and then love. They create beautiful puppets together, symbolizing their relationship.
One idea could be that Sakura uses her medical ninjutsu to heal Kankuro after he gets seriously injured in a battle against a powerful enemy. She has to overcome various challenges like limited supplies and the unique nature of Kankuro's puppet - related injuries.
A plot twist could be that the method Sakura uses to heal Kankuro has an unexpected side effect. For example, it gives him a temporary boost in his puppet - using abilities that he has to quickly learn to control.
One interesting thing is how their personalities might be explored in fanfiction. Kankuro is often seen as a bit of a trickster, while Tenten is determined. Their different traits could lead to some engaging storylines, like Tenten trying to get Kankuro to take things more seriously, or Kankuro teaching Tenten to be more flexible in her thinking.
I'm not sure specifically about 'gaara and kankuro lemon fanfiction'. Fanfiction can vary greatly in quality and availability. You could try searching on popular fanfiction websites like Archive of Our Own or FanFiction.net. However, make sure to abide by their terms and conditions.
Fanfiction can expand their relationship by creating new scenarios. For instance, it could place them in a situation where they have to rely on each other completely, like being trapped in a dangerous, unknown place. This would force them to open up and understand each other better, strengthening their relationship.
One way to discover great temari and kankuro fanfiction (even if it's not specifically 'lemon') is to follow some Naruto fanfiction groups on social media platforms. Members often post about new and interesting stories they've come across. You can also ask in those groups if anyone has any recommendations for temari and kankuro - centered fanfiction. Just be aware that not everyone might be into that pairing, so you might need to dig a bit deeper.