Legolas is friends with everything, everyone and anyone that somebody could possibly be friends with out of sheer determination alone.
As an elfling he made friends with all the rats in the kitchen, squirrels in the gardens, and learned to copy all the bird songs in the forest so he could talk to them.
He used to try and share his food with flesh-eating fish in a pond nearby to convince them it was better than meat (they didn’t believe him) but he is now the only elf that can go swimming with then without so much as a nibble.
Somehow he managed to befriend a hurt and territorial momma badger by coming to her clearing everyday to read to her. Going one step farther into the clearing everyday, until she trusted him. A month later he excitedly dragged his father to the clearing to meet an entire little army of Badgers who excitedly ran out of their hole to come see them.
On several occasions, Thranduil had gone looking for his rambunctious elflings on rainy days to find him mesmerized in a story told by a truly unfriendly and somewhat hostile librarian that had scarcely said eight entire words to Thranduil in the centuries they knew eachother. Until the day he sailed west, everytime that librarian saw Legolas he would stop for a short conversation, or casual greeting. Which was significantly more than any other elf ever got.
He would go for a short walk in the forest and come back with an orphaned wolf pup, go for a swim and return with a hawk with a broken wing. Send him on a simple message sending mission and he returned with some human boy named ‘Estel.’
Galion maintains that if they had given him enough time Legolas would have been able to charm Smaug into politely returning the gold and the mountain.
Coincidentally, this is also how Legolas manages to get Gimli into Valinor.
