Note: Warning: This is a humour fanfic, which means it is not meant to insult anyone, but to be funny. It contains very intense slash and below-belt punches in the humour department.
Have you ever wondered why in many slash stories nearly everyone is gay or bi, when in real life these are a minority? I have, so I wrote this to answer myself: it was an evil plot by Saruman!
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Sauron's Eye had been searching for the ringbearer, so he also got the first and heaviest load of Saruman's perverted magic. Frodo found himself suddenly staring at Legolas in a new way. Why hadn't he noticed before how beautiful the son of Thranduil was? Such golden hair, soft skin, large eyes... why, he was prettier than many a hobbit maiden!

Legolas felt eyes on him and found they were Frodo's. A quick look revealed everything to his elven instincts. His first emotion was unease: even in his long life, no man had ever stared at him so. But then the magic hit him, too. 'Why not?' He asked himself. For an elf, new things are rare and special, new experiences unforgettable treasures. And Frodo, he was something special, too. An elf-friend, a noble mind. Not to mention he was pretty, in an innocent, eager way. Almost like an adolescent elf, and just how long ago was it he had last met one, let alone kissed one...

The elf stood up and smiled at Frodo. The hobbit followed him away from the fire, onto a soft bed of moss hidden between large stones. They kissed, shyly at first, then with rising passion. Legolas opened Frodo's breeches, took them off him, touched him softly. Frodo sighed, he was already aroused. Legolas was taking off his own clothes, all of them. The cold seemed not to affect him, and indeed Frodo himself felt quite warm. Especially when he saw the elf naked. He was perfect, like a living statue of a... a young god, no less. And his member was long and slim, but very, very aroused. He put his hand on Frodo's butt.
'May I?' Legolas asked.
'Yes, oh, yes!'

After, they embraced, and Frodo wanted to kiss Legolas all over his perfect body. Suddenly the elf spoke:
'Would you like to have a go?'
'Are you joking? I'm spent.'
'Let me see about that.'
Legolas now started giving Frodo an intimate massage, and before long he felt he could, indeed, have a ride. His member was more than ready. Legolas now lay down and opened his legs, and Frodo entered him.
'Oh! You are so tight! Are you sure this doesn't hurt you?'
'No, it's wonderful.' His eyes were indeed full of pleasure.
Slowly at first, then with increasing speed, Frodo pushed and pulled his manhood inside his lover's beautiful flesh. This time he was slow in coming, he could feel like they were flying, even the ring was only a bad dream, and when he came at last he was totally exhausted. Legolas dressed him like a child, then whispered the words of an elven love song in his ear.