Well, how about for a meld, Red runs into S7, who have been prohibited from Aliens and are now investigating the super-natural. He helps them out, and they send him to look at an odd town called Sunnydale.

Hence him meeting Buffy and co, and becoming precious to both groups.

And the reason Buffy's group hate the arc? The arc track him down, and when Red see's them, he overreacts and runs away. Twins/Inferno/Prime pin him down to stop him, and Buffy stumbles across Red shrieking to be let go while someone much stonger than him holds him down.

May I friend you? I've quite enjoyed turning this innocent little bunny into the plot were-rabbit of doom.