You Had One Job, Fíli
Bad Babysitter: When both spiders and Elves attack and he doesn't notice his younger brother is missing until AFTER he hears him scream
Doesn't Share: When his younger brother is being attacked by spiders and doesn't even have a dagger…while he has nine.
Adolescent Advice: When he forgot to tell his younger brother the worst way to hit on a hot girl is by talking about your boner/making "in my pants" jokes if you actually want into her heart or trousers.
Bad Packer: When he didn't tell Dís to send Kíli something useful to remember her by…like a dagger.
The Harsh Truth: When he doesn't tell his younger brother that if terrible emo poetry and talking about missing your mother gets you the girl, it's most likely a pity fuck.
Don't Panic: When his younger brother gets shot by orcs and they all might die if a certain lever doesn't get pulled and he just sits in a barrel screaming his brother's name…twice.
Practicing Without a License: When his younger brother gets shot by orcs and he binds his leg rather than letting the only qualified healer among them take care of it.
Failed First Aid: When he lets his younger brother with an open wound swim through a sewer and crawl up a toilet.
Plays Too Nicely With Others: When orcs arrive while his younger brother is dying and he gives them a bear hug for showing their support.
Bad Bedside Manner: when he brings his younger brother a bowl of walnuts to rest in.
My Eyes are Up Here: When Tauriel is healing his dying younger brother, and all he can think is he just can't believe that boner reference/"in my pants" joke actually worked.
She Walks In Starlight In My Trippy Dreams: When he lets his younger brother flirt horribly under the influence of Elvish Medicine and doesn't even try to stop him.
Eye of the Cougar: When he doesn't tell Tauriel off for taking advantage of his not-even-legal little brother while he was unconscious/under the influence since she let him watch.