that's what we saw from the picture/.

yeah but theres another picture from the grandfather with the same quote

Just because the picture showed Blair and Serena, however it showed Blair at the front of the picture and Serena behind.
I took from that it would be Blair with a destroyed reputation and Dan because they are both people Serena is connected to, however Serena would choose to stand behind Blair rather than Dan- metaphorically, like support her, and this is shown literally in the picture. She slaps Dan in one of the promos, too, so...?

I over analyse everything, WHOOPS.

I doubt it would be the teacher's reputation, because she leaves next episode and nobody cares about her.

its either this or blair and rachel.

Just because the picture showed Blair and Serena, however it showed Blair at the front of the picture and Serena behind.
I took from that it would be Blair with a destroyed reputation and Dan because they are both people Serena is connected to, however Serena would choose to stand behind Blair rather than Dan- metaphorically, like support her, and this is shown literally in the picture. She slaps Dan in one of the promos, too, so...?

I over analyse everything, WHOOPS.

I doubt it would be the teacher's reputation, because she leaves next episode and nobody cares about her.
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You pretty much have everythig down. I also wan to add that Blair destroyed Dan's reputation which kind of destroyed her own at the same time. However, she is right. There is a things going on between Mrs. Carr and Dan. Even before the huge makeout. Mrs. Carr's reputation is going to be destroyed soon. I hate that woman!!!!!