Imagine Elrond and Elros cutting off Maedhros’s hair for magical purposes.
Being the only redheaded elf that they’ve seen, the twins believe his hair to be other worldy. And Maedhros being from Valinor only fuels their theory. Not to mention, Maglor’s own tall-tales about his elder brother’s hair incites the twin’s excitement.
“Bury it in the ground, and trees will spring from the earth. They will be tall and strong, like those from Valinor!”
The twins have always been obsessed with the Feanorian’s tales of Valinor, and to hear that they could have a piece of it simply by burying their father’s hair surprises them. So needless to say, they cut his hair off as he sleeps.
They don’t do a very good job at it, and leave it uneven and choppy, and in some places, quite bald. It is a nasty shock to Maedhros when he wakes up the next morning to find his hair missing. He knows who to hunt for, immediately, and doesn’t have to go far when he sees Elrond and Elros putting his hair in the ground and pouring water on top of the soil.
“Maglor says that your hair is magical, and that if we plant it in the ground we will grow trees from Valinor!”
His anger for the twins evaporates, and mentally goes through 100 scenarios as to how he can make Maglor pay.
“You know boys, Maglor’s hair is magical as well. If you cut it off and weave it into bracelets, you will sing just as well as him when you wear it.”
It’s safe to say that Maedhros gets his revenge the next morning.