I've always found Silver Spoon to be more sympathetic than Diamond Tiara at first glance, largely due to her reaction to Granny Smith's story in the classroom (she had a positive response as opposed to DT who was upset). Silver Spoon is really just a follower, and I have a feeling that Diamond probably tends to neglect her as a friend, which makes me feel bad for her. However, Diamond isn't without her problems either - as several people have pointed out, bullies usually do what they do because they're unhappy, particularly with their family lives. We've already sort of had a "bully redemption" episode with the whole Babs Seed thing, so it's sort of unlikely that we'll have a DT exposition episode anytime soon, but anyway.