...

Is it because we, being imaginative, individualists, didn't 'fit in' when we were young and like characters who seem a little awkward sometimes?

That would be my guess. We might wish we were heroes, but we know we're really sidekick material (which is okay by me. Willow is more interesting than Buffy any day. Of course Wills has her own sidekick now; does that make Tara Vila?)

Mistral

Hmmm, actor(tress) good looking, but played down by costumes; character notable for loyalty but doesn't trust the others to reciprocate; family background held character back from success... Yes, Tara is Vila.

Like Avon, Willow has computer skills that have been left out by scripts as she becomes more of a fighter/hero in her own right. (Willow slaying to vampires when she, Giles and Xander are filling in for Buffy; Willow the witch can acheive more than Willow the geek).

Buffy and Blake, hmm-- Buffy has been framed for crimes (charges later dropped).

Eerie.