Lalli always seemed elfish to me, with (almost) white hair and cat-like eyes.
Considering that Onni said that he belonged to the forest the Hotakainens would be forest elves in Tolkien's world. (humm, I must read The Silmarillion again, I barely remember all those kinds of Elves...)
Anyway, please write it!
Yep, forest elves, like Legolas. (I´m currently reading tLotR
I know I probably should have done it ages ago, but hey, better late then never. And it´s a really good book.) Also, elven-Lalli fanfiction, yes please! Though I kinda agree with wavewright, it only really makes sense when it´s in an AU. Which your idea seems to be Jitter, so great!
And because I´m late to the party but still want to say something about it, yes, that seagull-soapdisperser is glorius, it made me laugh out loud like an idiot and my brother question my sanity. So congrats :'D
Last but not least, Roos, that´s beautiful! It looks so realistic, especially the hair!