Why Ran and Lum work but Benten and Oyuki do not. Lum and Ran develop more than one simple gag and can do many different things. Benten is just the bitchy biker gal and Oyuki is just the cold distant bitch.
Ran can bake. Ran can cast high level magic. Ran can create robotic dolls. Ran has a rivalry with Lum. Ran wants to pursue Rei. Ran likes to play with Ataru to mess with Lum. Ran goes to school. In other words, they do things and aren't static characters.
>>2012Ran-Chan, it’s a call from your “cold distant bitch”
>>2025This feels like a threat, knowing the extremes she’ll get into
>>2012Ran can't cast magic.