Some classic Dawn-insert fics, arranged from shortest to longest.
Small Spaces by
deird1. Dawn and Wesley slowly become friends. Starts from season 3. G-rated.
Here Today, No Future Fears by
elviswhataguy. Dawn, Cordelia and others. Leaving. PG.
Fire and Stuff by Valerie X. Dawn and Spike trying to be bad, but getting distracted. Set during season 4. Rated R for swearing.
Telling Porkies (or read it
on AO3) by
beer_good_foamy. A different angle on "Becoming". Buffy thinks she has problems with Angel turning evil? Well, boo hoo. Dawn has to deal with a possessed stuffed pig trying to raise an army to end the world. PG-13.
Less Than Real by
zulu (or here is
AO3 link). When Dawn was real, she invited Faith into her life the very first time they met. Dawn/Faith, NC-17.